files.el 252 KB
Newer Older
Eric S. Raymond's avatar
Eric S. Raymond committed
1 2
;;; files.el --- file input and output commands for Emacs

3 4
;; Copyright (C) 1985, 1986, 1987, 1992, 1993, 1994, 1995, 1996,
;;   1997, 1998, 1999, 2000, 2001, 2002, 2003, 2004, 2005,
Glenn Morris's avatar
Glenn Morris committed
5
;;   2006, 2007, 2008, 2009 Free Software Foundation, Inc.
Roland McGrath's avatar
Roland McGrath committed
6

Eric S. Raymond's avatar
Eric S. Raymond committed
7 8
;; Maintainer: FSF

Roland McGrath's avatar
Roland McGrath committed
9 10
;; This file is part of GNU Emacs.

11
;; GNU Emacs is free software: you can redistribute it and/or modify
Roland McGrath's avatar
Roland McGrath committed
12
;; it under the terms of the GNU General Public License as published by
13 14
;; the Free Software Foundation, either version 3 of the License, or
;; (at your option) any later version.
Roland McGrath's avatar
Roland McGrath committed
15 16 17 18 19 20 21

;; 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
22
;; along with GNU Emacs.  If not, see <http://www.gnu.org/licenses/>.
Roland McGrath's avatar
Roland McGrath committed
23

24 25 26 27 28 29
;;; Commentary:

;; Defines most of Emacs's file- and directory-handling functions,
;; including basic file visiting, backup generation, link handling,
;; ITS-id version control, load- and write-hook handling, and the like.

Eric S. Raymond's avatar
Eric S. Raymond committed
30 31
;;; Code:

32 33
(eval-when-compile (require 'cl))

34 35
(defvar font-lock-keywords)

36 37
(defgroup backup nil
  "Backups of edited data files."
38
  :group 'files)
Roland McGrath's avatar
Roland McGrath committed
39

40
(defgroup find-file nil
41 42
  "Finding files."
  :group 'files)
43 44 45


(defcustom delete-auto-save-files t
46
  "Non-nil means delete auto-save file when a buffer is saved or killed.
47

Dave Love's avatar
Dave Love committed
48
Note that the auto-save file will not be deleted if the buffer is killed
49
when it has unsaved changes."
50 51 52 53
  :type 'boolean
  :group 'auto-save)

(defcustom directory-abbrev-alist
Roland McGrath's avatar
Roland McGrath committed
54
  nil
55
  "Alist of abbreviations for file directories.
Roland McGrath's avatar
Roland McGrath committed
56 57 58
A list of elements of the form (FROM . TO), each meaning to replace
FROM with TO when it appears in a directory name.  This replacement is
done when setting up the default directory of a newly visited file.
59
*Every* FROM string should start with \"\\\\`\".
Roland McGrath's avatar
Roland McGrath committed
60

61 62 63
FROM and TO should be equivalent names, which refer to the
same directory.  Do not use `~' in the TO strings;
they should be ordinary absolute directory names.
64

Roland McGrath's avatar
Roland McGrath committed
65 66
Use this feature when you have directories which you normally refer to
via absolute symbolic links.  Make TO the name of the link, and FROM
67 68 69 70 71 72 73
the name it is linked to."
  :type '(repeat (cons :format "%v"
		       :value ("" . "")
		       (regexp :tag "From")
		       (regexp :tag "To")))
  :group 'abbrev
  :group 'find-file)
Roland McGrath's avatar
Roland McGrath committed
74

Dan Nicolaescu's avatar
Dan Nicolaescu committed
75
(defcustom make-backup-files t
76
  "Non-nil means make a backup of a file the first time it is saved.
Roland McGrath's avatar
Roland McGrath committed
77 78 79 80 81 82 83 84 85 86 87 88 89
This can be done by renaming the file or by copying.

Renaming means that Emacs renames the existing file so that it is a
backup file, then writes the buffer into a new file.  Any other names
that the old file had will now refer to the backup file.  The new file
is owned by you and its group is defaulted.

Copying means that Emacs copies the existing file into the backup
file, then writes the buffer on top of the existing file.  Any other
names that the old file had will now refer to the new (edited) file.
The file's owner and group are unchanged.

The choice of renaming or copying is controlled by the variables
André Spiegel's avatar
André Spiegel committed
90 91 92
`backup-by-copying', `backup-by-copying-when-linked',
`backup-by-copying-when-mismatch' and
`backup-by-copying-when-privileged-mismatch'.  See also `backup-inhibited'."
93 94
  :type 'boolean
  :group 'backup)
Roland McGrath's avatar
Roland McGrath committed
95 96 97 98

;; Do this so that local variables based on the file name
;; are not overridden by the major mode.
(defvar backup-inhibited nil
99 100 101
  "Non-nil means don't make a backup, regardless of the other parameters.
This variable is intended for use by making it local to a buffer.
But it is local only if you make it local.")
Roland McGrath's avatar
Roland McGrath committed
102 103
(put 'backup-inhibited 'permanent-local t)

104
(defcustom backup-by-copying nil
105
 "Non-nil means always use copying to create backup files.
106
See documentation of variable `make-backup-files'."
107 108
  :type 'boolean
  :group 'backup)
Roland McGrath's avatar
Roland McGrath committed
109

110
(defcustom backup-by-copying-when-linked nil
111
 "Non-nil means use copying to create backups for files with multiple names.
Roland McGrath's avatar
Roland McGrath committed
112
This causes the alternate names to refer to the latest version as edited.
113
This variable is relevant only if `backup-by-copying' is nil."
114 115
  :type 'boolean
  :group 'backup)
Roland McGrath's avatar
Roland McGrath committed
116

117
(defcustom backup-by-copying-when-mismatch nil
118
  "Non-nil means create backups by copying if this preserves owner or group.
Roland McGrath's avatar
Roland McGrath committed
119 120 121 122
Renaming may still be used (subject to control of other variables)
when it would not result in changing the owner or group of the file;
that is, for files which are owned by you and whose group matches
the default for a new file created there by you.
123 124 125
This variable is relevant only if `backup-by-copying' is nil."
  :type 'boolean
  :group 'backup)
Roland McGrath's avatar
Roland McGrath committed
126

André Spiegel's avatar
André Spiegel committed
127
(defcustom backup-by-copying-when-privileged-mismatch 200
128
  "Non-nil means create backups by copying to preserve a privileged owner.
André Spiegel's avatar
André Spiegel committed
129 130 131 132 133 134 135 136 137 138 139
Renaming may still be used (subject to control of other variables)
when it would not result in changing the owner of the file or if the owner
has a user id greater than the value of this variable.  This is useful
when low-numbered uid's are used for special system users (such as root)
that must maintain ownership of certain files.
This variable is relevant only if `backup-by-copying' and
`backup-by-copying-when-mismatch' are nil."
  :type '(choice (const nil) integer)
  :group 'backup)

(defvar backup-enable-predicate 'normal-backup-enable-predicate
Roland McGrath's avatar
Roland McGrath committed
140
  "Predicate that looks at a file name and decides whether to make backups.
141
Called with an absolute file name as argument, it returns t to enable backup.")
Roland McGrath's avatar
Roland McGrath committed
142

143
(defcustom buffer-offer-save nil
144
  "Non-nil in a buffer means always offer to save buffer on exit.
André Spiegel's avatar
André Spiegel committed
145
Do so even if the buffer is not visiting a file.
146 147 148
Automatically local in all buffers."
  :type 'boolean
  :group 'backup)
Roland McGrath's avatar
Roland McGrath committed
149 150
(make-variable-buffer-local 'buffer-offer-save)

151
(defcustom find-file-existing-other-name t
152
  "Non-nil means find a file under alternative names, in existing buffers.
153
This means if any existing buffer is visiting the file you want
154 155 156
under another name, you get the existing buffer instead of a new buffer."
  :type 'boolean
  :group 'find-file)
157

158
(defcustom find-file-visit-truename nil
159
  "Non-nil means visit a file under its truename.
160
The truename of a file is found by chasing all links
161 162 163
both at the file level and at the levels of the containing directories."
  :type 'boolean
  :group 'find-file)
164
(put 'find-file-visit-truename 'safe-local-variable 'booleanp)
165

166
(defcustom revert-without-query nil
167
  "Specify which files should be reverted without query.
168 169
The value is a list of regular expressions.
If the file name matches one of these regular expressions,
170
then `revert-buffer' reverts the file without querying
171
if the file has changed on disk and you have not edited the buffer."
172
  :type '(repeat regexp)
173
  :group 'find-file)
174

175 176 177 178 179 180 181 182
(defvar buffer-file-number nil
  "The device number and file number of the file visited in the current buffer.
The value is a list of the form (FILENUM DEVNUM).
This pair of numbers uniquely identifies the file.
If the buffer is visiting a new file, the value is nil.")
(make-variable-buffer-local 'buffer-file-number)
(put 'buffer-file-number 'permanent-local t)

183
(defvar buffer-file-numbers-unique (not (memq system-type '(windows-nt)))
184
  "Non-nil means that `buffer-file-number' uniquely identifies files.")
185

186 187 188 189
(defvar buffer-file-read-only nil
  "Non-nil if visited file was read-only when visited.")
(make-variable-buffer-local 'buffer-file-read-only)

190
(defcustom temporary-file-directory
191 192 193 194 195
  (file-name-as-directory
   (cond ((memq system-type '(ms-dos windows-nt))
	  (or (getenv "TEMP") (getenv "TMPDIR") (getenv "TMP") "c:/temp"))
	 (t
	  (or (getenv "TMPDIR") (getenv "TMP") (getenv "TEMP") "/tmp"))))
196 197
  "The directory for writing temporary files."
  :group 'files
198
  :initialize 'custom-initialize-delay
199
  :type 'directory)
200

201
(defcustom small-temporary-file-directory
202 203 204 205
  (if (eq system-type 'ms-dos) (getenv "TMPDIR"))
  "The directory for writing small temporary files.
If non-nil, this directory is used instead of `temporary-file-directory'
by programs that create small temporary files.  This is for systems that
206 207
have fast storage with limited space, such as a RAM disk."
  :group 'files
208
  :initialize 'custom-initialize-delay
209
  :type '(choice (const nil) directory))
210 211

;; The system null device. (Should reference NULL_DEVICE from C.)
212
(defvar null-device (purecopy "/dev/null") "The system null device.")
213

214 215
(declare-function msdos-long-file-names "msdos.c")
(declare-function w32-long-file-name "w32proc.c")
Dan Nicolaescu's avatar
Dan Nicolaescu committed
216 217 218 219 220
(declare-function dired-get-filename "dired" (&optional localp no-error-if-not-filep))
(declare-function dired-unmark "dired" (arg))
(declare-function dired-do-flagged-delete "dired" (&optional nomessage))
(declare-function dos-8+3-filename "dos-fns" (filename))
(declare-function view-mode-disable "view" ())
Eli Zaretskii's avatar
Eli Zaretskii committed
221
(declare-function dosified-file-name "dos-fns" (file-name))
Dan Nicolaescu's avatar
Dan Nicolaescu committed
222

223 224
(defvar file-name-invalid-regexp
  (cond ((and (eq system-type 'ms-dos) (not (msdos-long-file-names)))
225
	 (purecopy
226
	 (concat "^\\([^A-Z[-`a-z]\\|..+\\)?:\\|" ; colon except after drive
227
		 "[+, ;=|<>\"?*]\\|\\[\\|\\]\\|"  ; invalid characters
228
		 "[\000-\037]\\|"		  ; control characters
229
		 "\\(/\\.\\.?[^/]\\)\\|"	  ; leading dots
230
		 "\\(/[^/.]+\\.[^/.]*\\.\\)")))	  ; more than a single dot
Juanma Barranquero's avatar
Juanma Barranquero committed
231
	((memq system-type '(ms-dos windows-nt cygwin))
232
	 (purecopy
233
	 (concat "^\\([^A-Z[-`a-z]\\|..+\\)?:\\|" ; colon except after drive
234 235
		 "[|<>\"?*\000-\037]")))		  ; invalid characters
	(t (purecopy "[\000]")))
236 237
  "Regexp recognizing file names which aren't allowed by the filesystem.")

238
(defcustom file-precious-flag nil
239
  "Non-nil means protect against I/O errors while saving files.
Karl Heuer's avatar
Karl Heuer committed
240
Some modes set this non-nil in particular buffers.
241 242 243 244 245 246 247

This feature works by writing the new contents into a temporary file
and then renaming the temporary file to replace the original.
In this way, any I/O error in writing leaves the original untouched,
and there is never any instant where the file is nonexistent.

Note that this feature forces backups to be made by copying.
Karl Heuer's avatar
Karl Heuer committed
248
Yet, at the same time, saving a precious file
249 250 251
breaks any hard links between it and other files.

This feature is advisory: for example, if the directory in which the
Chong Yidong's avatar
Chong Yidong committed
252
file is being saved is not writable, Emacs may ignore a non-nil value
Karl Fogel's avatar
Karl Fogel committed
253 254 255
of `file-precious-flag' and write directly into the file.

See also: `break-hardlink-on-save'."
256 257
  :type 'boolean
  :group 'backup)
Roland McGrath's avatar
Roland McGrath committed
258

Karl Fogel's avatar
Karl Fogel committed
259 260
(defcustom break-hardlink-on-save nil
  "Non-nil means when saving a file that exists under several names
261
\(i.e., has multiple hardlinks), break the hardlink associated with
Karl Fogel's avatar
Karl Fogel committed
262 263 264 265 266 267 268
`buffer-file-name' and write to a new file, so that the other
instances of the file are not affected by the save.

If `buffer-file-name' refers to a symlink, do not break the symlink.

Unlike `file-precious-flag', `break-hardlink-on-save' is not advisory.
For example, if the directory in which a file is being saved is not
Chong Yidong's avatar
Chong Yidong committed
269
itself writable, then error instead of saving in some
Karl Fogel's avatar
Karl Fogel committed
270 271 272 273
hardlink-nonbreaking way.

See also `backup-by-copying' and `backup-by-copying-when-linked'."
  :type 'boolean
274 275
  :group 'files
  :version "23.1")
Karl Fogel's avatar
Karl Fogel committed
276

277
(defcustom version-control nil
278
  "Control use of version numbers for backup files.
279 280 281
When t, make numeric backup versions unconditionally.
When nil, make them for files that have some already.
The value `never' means do not make them."
282 283 284
  :type '(choice (const :tag "Never" never)
		 (const :tag "If existing" nil)
		 (other :tag "Always" t))
285 286
  :group 'backup
  :group 'vc)
287 288
(put 'version-control 'safe-local-variable
     '(lambda (x) (or (booleanp x) (equal x 'never))))
289 290

(defcustom dired-kept-versions 2
291
  "When cleaning directory, number of versions to keep."
292 293 294 295 296
  :type 'integer
  :group 'backup
  :group 'dired)

(defcustom delete-old-versions nil
297
  "If t, delete excess backup versions silently.
298 299 300
If nil, ask confirmation.  Any other value prevents any trimming."
  :type '(choice (const :tag "Delete" t)
		 (const :tag "Ask" nil)
301
		 (other :tag "Leave" other))
302 303 304
  :group 'backup)

(defcustom kept-old-versions 2
305
  "Number of oldest versions to keep when a new numbered backup is made."
306 307
  :type 'integer
  :group 'backup)
308
(put 'kept-old-versions 'safe-local-variable 'integerp)
309 310

(defcustom kept-new-versions 2
311
  "Number of newest versions to keep when a new numbered backup is made.
312 313 314
Includes the new backup.  Must be > 0"
  :type 'integer
  :group 'backup)
315
(put 'kept-new-versions 'safe-local-variable 'integerp)
Roland McGrath's avatar
Roland McGrath committed
316

317
(defcustom require-final-newline nil
318
  "Whether to add a newline automatically at the end of the file.
319 320 321 322 323

A value of t means do this only when the file is about to be saved.
A value of `visit' means do this right after the file is visited.
A value of `visit-save' means do it at both of those times.
Any other non-nil value means ask user whether to add a newline, when saving.
324
A value of nil means don't add newlines.
325 326 327 328 329 330

Certain major modes set this locally to the value obtained
from `mode-require-final-newline'."
  :type '(choice (const :tag "When visiting" visit)
		 (const :tag "When saving" t)
		 (const :tag "When visiting or saving" visit-save)
331
		 (const :tag "Don't add newlines" nil)
332
		 (other :tag "Ask each time" ask))
333
  :group 'editing-basics)
Roland McGrath's avatar
Roland McGrath committed
334

335
(defcustom mode-require-final-newline t
336
  "Whether to add a newline at end of file, in certain major modes.
337
Those modes set `require-final-newline' to this value when you enable them.
338
They do so because they are often used for files that are supposed
339 340 341 342 343
to end in newlines, and the question is how to arrange that.

A value of t means do this only when the file is about to be saved.
A value of `visit' means do this right after the file is visited.
A value of `visit-save' means do it at both of those times.
344 345
Any other non-nil value means ask user whether to add a newline, when saving.

346 347 348 349
A value of nil means do not add newlines.  That is a risky choice in this
variable since this value is used for modes for files that ought to have
final newlines.  So if you set this to nil, you must explicitly check and
add a final newline, whenever you save a file that really needs one."
350 351 352
  :type '(choice (const :tag "When visiting" visit)
		 (const :tag "When saving" t)
		 (const :tag "When visiting or saving" visit-save)
353 354
		 (const :tag "Don't add newlines" nil)
		 (other :tag "Ask each time" ask))
355
  :group 'editing-basics
356
  :version "22.1")
357

358
(defcustom auto-save-default t
359
  "Non-nil says by default do auto-saving of every file-visiting buffer."
360 361
  :type 'boolean
  :group 'auto-save)
Roland McGrath's avatar
Roland McGrath committed
362

André Spiegel's avatar
André Spiegel committed
363
(defcustom auto-save-file-name-transforms
364
  `(("\\`/[^/]*:\\([^/]*/\\)*\\([^/]*\\)\\'"
365 366
     ;; Don't put "\\2" inside expand-file-name, since it will be
     ;; transformed to "/2" on DOS/Windows.
367
     ,(concat temporary-file-directory "\\2") t))
368
  "Transforms to apply to buffer file name before making auto-save file name.
369
Each transform is a list (REGEXP REPLACEMENT UNIQUIFY):
André Spiegel's avatar
André Spiegel committed
370 371 372
REGEXP is a regular expression to match against the file name.
If it matches, `replace-match' is used to replace the
matching part with REPLACEMENT.
373
If the optional element UNIQUIFY is non-nil, the auto-save file name is
374
constructed by taking the directory part of the replaced file-name,
375 376 377 378
concatenated with the buffer file name with all directory separators
changed to `!' to prevent clashes.  This will not work
correctly if your filesystem truncates the resulting name.

André Spiegel's avatar
André Spiegel committed
379 380 381 382
All the transforms in the list are tried, in the order they are listed.
When one transform applies, its result is final;
no further transforms are tried.

383 384
The default value is set up to put the auto-save file into the
temporary directory (see the variable `temporary-file-directory') for
385 386 387 388
editing a remote file.

On MS-DOS filesystems without long names this variable is always
ignored."
André Spiegel's avatar
André Spiegel committed
389
  :group 'auto-save
390 391
  :type '(repeat (list (string :tag "Regexp") (string :tag "Replacement")
					   (boolean :tag "Uniquify")))
392
  :initialize 'custom-initialize-delay
André Spiegel's avatar
André Spiegel committed
393 394
  :version "21.1")

395
(defcustom save-abbrevs t
396
  "Non-nil means save word abbrevs too when files are saved.
397 398
If `silently', don't ask the user before saving."
  :type '(choice (const t) (const nil) (const silently))
399
  :group 'abbrev)
Roland McGrath's avatar
Roland McGrath committed
400

401
(defcustom find-file-run-dired t
402
  "Non-nil means allow `find-file' to visit directories.
André Spiegel's avatar
André Spiegel committed
403
To visit the directory, `find-file' runs `find-directory-functions'."
404 405
  :type 'boolean
  :group 'find-file)
Roland McGrath's avatar
Roland McGrath committed
406

André Spiegel's avatar
André Spiegel committed
407
(defcustom find-directory-functions '(cvs-dired-noselect dired-noselect)
408
  "List of functions to try in sequence to visit a directory.
André Spiegel's avatar
André Spiegel committed
409 410 411 412 413
Each function is called with the directory name as the sole argument
and should return either a buffer or nil."
  :type '(hook :options (cvs-dired-noselect dired-noselect))
  :group 'find-file)

414 415
;;;It is not useful to make this a local variable.
;;;(put 'find-file-not-found-hooks 'permanent-local t)
Stefan Monnier's avatar
Stefan Monnier committed
416
(defvar find-file-not-found-functions nil
Roland McGrath's avatar
Roland McGrath committed
417 418
  "List of functions to be called for `find-file' on nonexistent file.
These functions are called as soon as the error is detected.
André Spiegel's avatar
André Spiegel committed
419
Variable `buffer-file-name' is already set up.
Roland McGrath's avatar
Roland McGrath committed
420
The functions are called in the order given until one of them returns non-nil.")
421 422
(define-obsolete-variable-alias 'find-file-not-found-hooks
    'find-file-not-found-functions "22.1")
Roland McGrath's avatar
Roland McGrath committed
423

424 425
;;;It is not useful to make this a local variable.
;;;(put 'find-file-hooks 'permanent-local t)
426
(define-obsolete-variable-alias 'find-file-hooks 'find-file-hook "22.1")
Dave Love's avatar
Dave Love committed
427
(defcustom find-file-hook nil
Roland McGrath's avatar
Roland McGrath committed
428 429
  "List of functions to be called after a buffer is loaded from a file.
The buffer's local variables (if any) will have been processed before the
Dave Love's avatar
Dave Love committed
430 431 432 433
functions are called."
  :group 'find-file
  :type 'hook
  :options '(auto-insert)
434
  :version "22.1")
Roland McGrath's avatar
Roland McGrath committed
435

Stefan Monnier's avatar
Stefan Monnier committed
436
(defvar write-file-functions nil
Roland McGrath's avatar
Roland McGrath committed
437 438
  "List of functions to be called before writing out a buffer to a file.
If one of them returns non-nil, the file is considered already written
Jim Blandy's avatar
Jim Blandy committed
439 440
and the rest are not called.
These hooks are considered to pertain to the visited file.
Stefan Monnier's avatar
Stefan Monnier committed
441 442 443 444
So any buffer-local binding of this variable is discarded if you change
the visited file name with \\[set-visited-file-name], but not when you
change the major mode.

445 446 447 448 449
This hook is not run if any of the functions in
`write-contents-functions' returns non-nil.  Both hooks pertain
to how to save a buffer to file, for instance, choosing a suitable
coding system and setting mode bits.  (See Info
node `(elisp)Saving Buffers'.)  To perform various checks or
450
updates before the buffer is saved, use `before-save-hook'.")
Stefan Monnier's avatar
Stefan Monnier committed
451
(put 'write-file-functions 'permanent-local t)
452
(define-obsolete-variable-alias 'write-file-hooks 'write-file-functions "22.1")
Stefan Monnier's avatar
Stefan Monnier committed
453 454

(defvar local-write-file-hooks nil)
455 456
(make-variable-buffer-local 'local-write-file-hooks)
(put 'local-write-file-hooks 'permanent-local t)
457
(make-obsolete-variable 'local-write-file-hooks 'write-file-functions "22.1")
Jim Blandy's avatar
Jim Blandy committed
458

Stefan Monnier's avatar
Stefan Monnier committed
459
(defvar write-contents-functions nil
Jim Blandy's avatar
Jim Blandy committed
460 461
  "List of functions to be called before writing out a buffer to a file.
If one of them returns non-nil, the file is considered already written
462 463
and the rest are not called and neither are the functions in
`write-file-functions'.
464 465 466 467

This variable is meant to be used for hooks that pertain to the
buffer's contents, not to the particular visited file; thus,
`set-visited-file-name' does not clear this variable; but changing the
468 469
major mode does clear it.

470 471 472 473 474
For hooks that _do_ pertain to the particular visited file, use
`write-file-functions'.  Both this variable and
`write-file-functions' relate to how a buffer is saved to file.
To perform various checks or updates before the buffer is saved,
use `before-save-hook'.")
Stefan Monnier's avatar
Stefan Monnier committed
475
(make-variable-buffer-local 'write-contents-functions)
476 477
(define-obsolete-variable-alias 'write-contents-hooks
    'write-contents-functions "22.1")
Roland McGrath's avatar
Roland McGrath committed
478

479
(defcustom enable-local-variables t
480
  "Control use of local variables in files you visit.
481
The value can be t, nil, :safe, :all, or something else.
482 483

A value of t means file local variables specifications are obeyed
484 485
if all the specified variable values are safe; if any values are
not safe, Emacs queries you, once, whether to set them all.
486 487 488
\(When you say yes to certain values, they are remembered as safe.)

:safe means set the safe variables, and ignore the rest.
489 490
:all means set all variables, whether safe or not.
 (Don't set it permanently to :all.)
491
A value of nil means always ignore the file local variables.
492 493

Any other value means always query you once whether to set them all.
494 495
\(When you say yes to certain values, they are remembered as safe, but
this has no effect when `enable-local-variables' is \"something else\".)
496

497 498
This variable also controls use of major modes specified in
a -*- line.
Roland McGrath's avatar
Roland McGrath committed
499

500 501 502
The command \\[normal-mode], when used interactively,
always obeys file local variable specifications and the -*- line,
and ignores this variable."
503
  :risky t
504
  :type '(choice (const :tag "Query Unsafe" t)
505
		 (const :tag "Safe Only" :safe)
506
		 (const :tag "Do all" :all)
507
		 (const :tag "Ignore" nil)
508
		 (other :tag "Query" other))
509
  :group 'find-file)
Roland McGrath's avatar
Roland McGrath committed
510

511 512
(defvar local-enable-local-variables t
  "Like `enable-local-variables' but meant for buffer-local bindings.
513
The meaningful values are nil and non-nil.  The default is non-nil.
514
If a major mode sets this to nil, buffer-locally, then any local
515 516 517 518
variables list in the file will be ignored.

This variable does not affect the use of major modes
specified in a -*- line.")
519

520
(defcustom enable-local-eval 'maybe
521
  "Control processing of the \"variable\" `eval' in a file's local variables.
522
The value can be t, nil or something else.
523
A value of t means obey `eval' variables.
524
A value of nil means ignore them; anything else means query."
525
  :risky t
526 527
  :type '(choice (const :tag "Obey" t)
		 (const :tag "Ignore" nil)
528
		 (other :tag "Query" other))
529
  :group 'find-file)
Roland McGrath's avatar
Roland McGrath committed
530 531 532

;; Avoid losing in versions where CLASH_DETECTION is disabled.
(or (fboundp 'lock-buffer)
533
    (defalias 'lock-buffer 'ignore))
Roland McGrath's avatar
Roland McGrath committed
534
(or (fboundp 'unlock-buffer)
535
    (defalias 'unlock-buffer 'ignore))
536 537
(or (fboundp 'file-locked-p)
    (defalias 'file-locked-p 'ignore))
538

539
(defcustom view-read-only nil
540
  "Non-nil means buffers visiting files read-only do so in view mode.
541 542 543 544
In fact, this means that all read-only buffers normally have
View mode enabled, including buffers that are read-only because
you visit a file you cannot alter, and buffers you make read-only
using \\[toggle-read-only]."
545 546
  :type 'boolean
  :group 'view)
547

548
(defvar file-name-history nil
549 550 551 552
  "History list of file names entered in the minibuffer.

Maximum length of the history list is determined by the value
of `history-length', which see.")
553

554
(put 'ange-ftp-completion-hook-function 'safe-magic t)
555
(defun ange-ftp-completion-hook-function (op &rest args)
André Spiegel's avatar
André Spiegel committed
556 557 558 559
  "Provides support for ange-ftp host name completion.
Runs the usual ange-ftp hook, but only for completion operations."
  ;; Having this here avoids the need to load ange-ftp when it's not
  ;; really in use.
560 561
  (if (memq op '(file-name-completion file-name-all-completions))
      (apply 'ange-ftp-hook-function op args)
562 563 564 565 566
    (let ((inhibit-file-name-handlers
	   (cons 'ange-ftp-completion-hook-function
		 (and (eq inhibit-file-name-operation op)
		      inhibit-file-name-handlers)))
	  (inhibit-file-name-operation op))
567
      (apply op args))))
568 569

(defun convert-standard-filename (filename)
570
  "Convert a standard file's name to something suitable for the OS.
571 572 573
This means to guarantee valid names and perhaps to canonicalize
certain patterns.

574 575 576 577
FILENAME should be an absolute file name since the conversion rules
sometimes vary depending on the position in the file name.  E.g. c:/foo
is a valid DOS file name, but c:/bar/c:/foo is not.

578 579
This function's standard definition is trivial; it just returns
the argument.  However, on Windows and DOS, replace invalid
580 581 582
characters.  On DOS, make sure to obey the 8.3 limitations.
In the native Windows build, turn Cygwin names into native names,
and also turn slashes into backslashes if the shell requires it (see
583 584 585
`w32-shell-dos-semantics').

See Info node `(elisp)Standard File Names' for more details."
586 587 588 589 590
  (if (eq system-type 'cygwin)
      (let ((name (copy-sequence filename))
	    (start 0))
	;; Replace invalid filename characters with !
	(while (string-match "[?*:<>|\"\000-\037]" name start)
591
	       (aset name (match-beginning 0) ?!)
592 593 594
	  (setq start (match-end 0)))
	name)
    filename))
595 596 597 598

(defun read-directory-name (prompt &optional dir default-dirname mustmatch initial)
  "Read directory name, prompting with PROMPT and completing in directory DIR.
Value is not expanded---you must call `expand-file-name' yourself.
599 600
Default name to DEFAULT-DIRNAME if user exits with the same
non-empty string that was inserted by this function.
601 602
 (If DEFAULT-DIRNAME is omitted, DIR combined with INITIAL is used,
  or just DIR if INITIAL is nil.)
603 604 605
If the user exits with an empty minibuffer, this function returns
an empty string.  (This can only happen if the user erased the
pre-inserted contents or if `insert-default-directory' is nil.)
606 607 608
Fourth arg MUSTMATCH non-nil means require existing directory's name.
 Non-nil and non-t means also require confirmation after completion.
Fifth arg INITIAL specifies text to start with.
609 610
DIR should be an absolute directory name.  It defaults to
the value of `default-directory'."
611 612
  (unless dir
    (setq dir default-directory))
613
  (read-file-name prompt dir (or default-dirname
614 615 616
				 (if initial (expand-file-name initial dir)
				   dir))
		  mustmatch initial
617 618
		  'file-directory-p))

Roland McGrath's avatar
Roland McGrath committed
619 620 621 622 623 624

(defun pwd ()
  "Show the current default directory."
  (interactive nil)
  (message "Directory %s" default-directory))

625 626
(defvar cd-path nil
  "Value of the CDPATH environment variable, as a list.
627
Not actually set up until the first time you use it.")
628 629

(defun parse-colon-path (cd-path)
630
  "Explode a search path into a list of directory names.
631 632
Directories are separated by occurrences of `path-separator'
\(which is colon in GNU and GNU-like systems)."
André Spiegel's avatar
André Spiegel committed
633
  ;; We could use split-string here.
634
  (and cd-path
635
       (let (cd-list (cd-start 0) cd-colon)
636 637
	 (setq cd-path (concat cd-path path-separator))
	 (while (setq cd-colon (string-match path-separator cd-path cd-start))
638
	   (setq cd-list
639
		 (nconc cd-list
640 641 642
			(list (if (= cd-start cd-colon)
				   nil
				(substitute-in-file-name
643 644
				 (file-name-as-directory
				  (substring cd-path cd-start cd-colon)))))))
645 646 647 648
	   (setq cd-start (+ cd-colon 1)))
	 cd-list)))

(defun cd-absolute (dir)
649
  "Change current directory to given absolute file name DIR."
650 651
  ;; Put the name into directory syntax now,
  ;; because otherwise expand-file-name may give some bad results.
Dan Nicolaescu's avatar
Dan Nicolaescu committed
652
  (setq dir (file-name-as-directory dir))
653 654 655 656 657 658
  ;; We used to additionally call abbreviate-file-name here, for an
  ;; unknown reason.  Problem is that most buffers are setup
  ;; without going through cd-absolute and don't call
  ;; abbreviate-file-name on their default-directory, so the few that
  ;; do end up using a superficially different directory.
  (setq dir (expand-file-name dir))
Roland McGrath's avatar
Roland McGrath committed
659
  (if (not (file-directory-p dir))
660 661
      (if (file-exists-p dir)
	  (error "%s is not a directory" dir)
662
	(error "%s: no such directory" dir))
663 664 665
    (unless (file-executable-p dir)
      (error "Cannot cd to %s:  Permission denied" dir))
    (setq default-directory dir)
666
    (setq list-buffers-directory dir)))
Roland McGrath's avatar
Roland McGrath committed
667

668 669
(defun cd (dir)
  "Make DIR become the current buffer's default directory.
670 671
If your environment includes a `CDPATH' variable, try each one of
that list of directories (separated by occurrences of
672 673
`path-separator') when resolving a relative directory name.
The path separator is colon in GNU and GNU-like systems."
674
  (interactive
675
   (list (read-directory-name "Change default directory: "
676 677 678
			 default-directory default-directory
			 (and (member cd-path '(nil ("./")))
			      (null (getenv "CDPATH"))))))
679 680 681 682 683 684
  (if (file-name-absolute-p dir)
      (cd-absolute (expand-file-name dir))
    (if (null cd-path)
	(let ((trypath (parse-colon-path (getenv "CDPATH"))))
	  (setq cd-path (or trypath (list "./")))))
    (if (not (catch 'found
685
	       (mapc
686 687 688 689 690 691 692 693 694
		(function (lambda (x)
			    (let ((f (expand-file-name (concat x dir))))
			      (if (file-directory-p f)
				  (progn
				    (cd-absolute f)
				    (throw 'found t))))))
		cd-path)
	       nil))
	(error "No such directory found via CDPATH environment variable"))))
695

Roland McGrath's avatar
Roland McGrath committed
696 697
(defun load-file (file)
  "Load the Lisp file named FILE."
698 699
  ;; This is a case where .elc makes a lot of sense.
  (interactive (list (let ((completion-ignored-extensions
Dave Love's avatar
Dave Love committed
700
			    (remove ".elc" completion-ignored-extensions)))
701 702
		       (read-file-name "Load file: "))))
  (load (expand-file-name file) nil nil t))
Roland McGrath's avatar
Roland McGrath committed
703

Stefan Monnier's avatar
Stefan Monnier committed
704 705
(defun locate-file (filename path &optional suffixes predicate)
  "Search for FILENAME through PATH.
Eli Zaretskii's avatar
Eli Zaretskii committed
706 707 708 709
If found, return the absolute file name of FILENAME, with its suffixes;
otherwise return nil.
PATH should be a list of directories to look in, like the lists in
`exec-path' or `load-path'.
Stefan Monnier's avatar
Stefan Monnier committed
710 711
If SUFFIXES is non-nil, it should be a list of suffixes to append to
file name when searching.  If SUFFIXES is nil, it is equivalent to '(\"\").
Eli Zaretskii's avatar
Eli Zaretskii committed
712
Use '(\"/\") to disable PATH search, but still try the suffixes in SUFFIXES.
Stefan Monnier's avatar
Stefan Monnier committed
713
If non-nil, PREDICATE is used instead of `file-readable-p'.
Richard M. Stallman's avatar
Richard M. Stallman committed
714 715 716 717 718 719
PREDICATE can also be an integer to pass to the `access' system call,
in which case file-name handlers are ignored.  This usage is deprecated.

For compatibility, PREDICATE can also be one of the symbols
`executable', `readable', `writable', or `exists', or a list of
one or more of those symbols."
Stefan Monnier's avatar
Stefan Monnier committed
720 721 722 723 724 725 726 727 728
  (if (and predicate (symbolp predicate) (not (functionp predicate)))
      (setq predicate (list predicate)))
  (when (and (consp predicate) (not (functionp predicate)))
    (setq predicate
	  (logior (if (memq 'executable predicate) 1 0)
		  (if (memq 'writable predicate) 2 0)
		  (if (memq 'readable predicate) 4 0))))
  (locate-file-internal filename path suffixes predicate))

729 730
(defun locate-file-completion-table (dirs suffixes string pred action)
  "Do completion for file names passed to `locate-file'."
731 732
  (cond
   ((file-name-absolute-p string)
733 734 735 736
    ;; FIXME: maybe we should use completion-file-name-table instead,
    ;; tho at least for `load', the arg is passed through
    ;; substitute-in-file-name for historical reasons.
    (read-file-name-internal string pred action))
737 738
   ((eq (car-safe action) 'boundaries)
    (let ((suffix (cdr action)))
739
      (list* 'boundaries
740 741 742 743
             (length (file-name-directory string))
             (let ((x (file-name-directory suffix)))
               (if x (1- (length x)) (length suffix))))))
   (t
744
    (let ((names nil)
745
	  (suffix (concat (regexp-opt suffixes t) "\\'"))
746 747
	  (string-dir (file-name-directory string))
          (string-file (file-name-nondirectory string)))
748
      (dolist (dir dirs)
749 750
	(unless dir
	  (setq dir default-directory))
751 752 753
	(if string-dir (setq dir (expand-file-name string-dir dir)))
	(when (file-directory-p dir)
	  (dolist (file (file-name-all-completions
754 755
			 string-file dir))
	    (push file names)
756 757
	    (when (string-match suffix file)
	      (setq file (substring file 0 (match-beginning 0)))
758 759 760
              (push file names)))))
      (completion-table-with-context
       string-dir names string-file pred action)))))
761 762 763 764 765 766 767 768

(defun locate-file-completion (string path-and-suffixes action)
  "Do completion for file names passed to `locate-file'.
PATH-AND-SUFFIXES is a pair of lists, (DIRECTORIES . SUFFIXES)."
  (locate-file-completion-table (car path-and-suffixes)
                                (cdr path-and-suffixes)
                                string nil action))
(make-obsolete 'locate-file-completion 'locate-file-completion-table "23.1")
769

770
(defvar locate-dominating-stop-dir-regexp
771
  (purecopy "\\`\\(?:[\\/][\\/][^\\/]+[\\/]\\|/\\(?:net\\|afs\\|\\.\\.\\.\\)/\\)\\'")
772 773 774 775 776
  "Regexp of directory names which stop the search in `locate-dominating-file'.
Any directory whose name matches this regexp will be treated like
a kind of root directory by `locate-dominating-file' which will stop its search
when it bumps into it.
The default regexp prevents fruitless and time-consuming attempts to find
777 778
special files in directories in which filenames are interpreted as hostnames,
or mount points potentially requiring authentication as a different user.")
779 780 781 782 783 784 785 786 787 788 789 790 791 792 793 794 795 796 797 798 799 800 801 802 803 804 805 806 807 808 809 810 811

;; (defun locate-dominating-files (file regexp)
;;   "Look up the directory hierarchy from FILE for a file matching REGEXP.
;; Stop at the first parent where a matching file is found and return the list
;; of files that that match in this directory."
;;   (catch 'found
;;     ;; `user' is not initialized yet because `file' may not exist, so we may
;;     ;; have to walk up part of the hierarchy before we find the "initial UID".
;;     (let ((user nil)
;;           ;; Abbreviate, so as to stop when we cross ~/.
;;           (dir (abbreviate-file-name (file-name-as-directory file)))
;;           files)
;;       (while (and dir
;;                   ;; As a heuristic, we stop looking up the hierarchy of
;;                   ;; directories as soon as we find a directory belonging to
;;                   ;; another user.  This should save us from looking in
;;                   ;; things like /net and /afs.  This assumes that all the
;;                   ;; files inside a project belong to the same user.
;;                   (let ((prev-user user))
;;                     (setq user (nth 2 (file-attributes dir)))
;;                     (or (null prev-user) (equal user prev-user))))
;;         (if (setq files (condition-case nil
;; 			    (directory-files dir 'full regexp 'nosort)
;; 			  (error nil)))
;;             (throw 'found files)
;;           (if (equal dir
;;                      (setq dir (file-name-directory
;;                                 (directory-file-name dir))))
;;               (setq dir nil))))
;;       nil)))

(defun locate-dominating-file (file name)
  "Look up the directory hierarchy from FILE for a file named NAME.
812 813
Stop at the first parent directory containing a file NAME,
and return the directory.  Return nil if not found."
814 815 816
  ;; We used to use the above locate-dominating-files code, but the
  ;; directory-files call is very costly, so we're much better off doing
  ;; multiple calls using the code in here.
817
  ;;
818 819 820 821 822 823 824 825 826 827 828 829 830 831 832 833 834 835 836 837 838 839 840 841 842 843 844 845 846 847 848
  ;; Represent /home/luser/foo as ~/foo so that we don't try to look for
  ;; `name' in /home or in /.
  (setq file (abbreviate-file-name file))
  (let ((root nil)
        (prev-file file)
        ;; `user' is not initialized outside the loop because
        ;; `file' may not exist, so we may have to walk up part of the
        ;; hierarchy before we find the "initial UID".
        (user nil)
        try)
    (while (not (or root
                    (null file)
                    ;; FIXME: Disabled this heuristic because it is sometimes
                    ;; inappropriate.
                    ;; As a heuristic, we stop looking up the hierarchy of
                    ;; directories as soon as we find a directory belonging
                    ;; to another user.  This should save us from looking in
                    ;; things like /net and /afs.  This assumes that all the
                    ;; files inside a project belong to the same user.
                    ;; (let ((prev-user user))
                    ;;   (setq user (nth 2 (file-attributes file)))
                    ;;   (and prev-user (not (equal user prev-user))))
                    (string-match locate-dominating-stop-dir-regexp file)))
      (setq try (file-exists-p (expand-file-name name file)))
      (cond (try (setq root file))
            ((equal file (setq prev-file file
                               file (file-name-directory
                                     (directory-file-name file))))
             (setq file nil))))
    root))

849

850 851 852 853 854 855 856
(defun executable-find (command)
  "Search for COMMAND in `exec-path' and return the absolute file name.
Return nil if COMMAND is not found anywhere in `exec-path'."
  ;; Use 1 rather than file-executable-p to better match the behavior of
  ;; call-process.
  (locate-file command exec-path exec-suffixes 1))

Roland McGrath's avatar
Roland McGrath committed
857
(defun load-library (library)
858
  "Load the Emacs Lisp library named LIBRARY.
859 860 861