files.el 278 KB
Newer Older
Eric S. Raymond's avatar
Eric S. Raymond committed
1 2
;;; files.el --- file input and output commands for Emacs

3
;; Copyright (C) 1985-1987, 1992-2013 Free Software Foundation, Inc.
Roland McGrath's avatar
Roland McGrath committed
4

Eric S. Raymond's avatar
Eric S. Raymond committed
5
;; Maintainer: FSF
6
;; Package: emacs
Eric S. Raymond's avatar
Eric S. Raymond committed
7

Roland McGrath's avatar
Roland McGrath committed
8 9
;; This file is part of GNU Emacs.

10
;; GNU Emacs is free software: you can redistribute it and/or modify
Roland McGrath's avatar
Roland McGrath committed
11
;; it under the terms of the GNU General Public License as published by
12 13
;; the Free Software Foundation, either version 3 of the License, or
;; (at your option) any later version.
Roland McGrath's avatar
Roland McGrath committed
14 15 16 17 18 19 20

;; 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
21
;; along with GNU Emacs.  If not, see <http://www.gnu.org/licenses/>.
Roland McGrath's avatar
Roland McGrath committed
22

23 24
;;; Commentary:

Glenn Morris's avatar
Glenn Morris committed
25
;; Defines most of Emacs's file- and directory-handling functions,
26 27 28
;; 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
29 30
;;; Code:

31 32
(defvar font-lock-keywords)

33 34
(defgroup backup nil
  "Backups of edited data files."
35
  :group 'files)
Roland McGrath's avatar
Roland McGrath committed
36

37
(defgroup find-file nil
38 39
  "Finding files."
  :group 'files)
40 41 42


(defcustom delete-auto-save-files t
43
  "Non-nil means delete auto-save file when a buffer is saved or killed.
44

Dave Love's avatar
Dave Love committed
45
Note that the auto-save file will not be deleted if the buffer is killed
46
when it has unsaved changes."
47 48 49 50
  :type 'boolean
  :group 'auto-save)

(defcustom directory-abbrev-alist
Roland McGrath's avatar
Roland McGrath committed
51
  nil
52
  "Alist of abbreviations for file directories.
Roland McGrath's avatar
Roland McGrath committed
53 54 55
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.
Glenn Morris's avatar
Glenn Morris committed
56 57 58 59

FROM is matched against directory names anchored at the first
character, so it should start with a \"\\\\`\", or, if directory
names cannot have embedded newlines, with a \"^\".
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
the name it is linked to."
  :type '(repeat (cons :format "%v"
69
		       :value ("\\`" . "")
70
		       (regexp :tag "From")
71
		       (string :tag "To")))
72 73
  :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 t
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
This variable is relevant only if `backup-by-copying' is nil."
124
  :version "24.1"
125 126
  :type 'boolean
  :group 'backup)
127
(put 'backup-by-copying-when-mismatch 'permanent-local t)
Roland McGrath's avatar
Roland McGrath committed
128

André Spiegel's avatar
André Spiegel committed
129
(defcustom backup-by-copying-when-privileged-mismatch 200
130
  "Non-nil means create backups by copying to preserve a privileged owner.
André Spiegel's avatar
André Spiegel committed
131 132 133 134 135 136 137 138 139 140 141
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
142
  "Predicate that looks at a file name and decides whether to make backups.
143
Called with an absolute file name as argument, it returns t to enable backup.")
Roland McGrath's avatar
Roland McGrath committed
144

145
(defcustom buffer-offer-save nil
146
  "Non-nil in a buffer means always offer to save buffer on exit.
André Spiegel's avatar
André Spiegel committed
147
Do so even if the buffer is not visiting a file.
148 149 150
Automatically local in all buffers."
  :type 'boolean
  :group 'backup)
Roland McGrath's avatar
Roland McGrath committed
151
(make-variable-buffer-local 'buffer-offer-save)
152
(put 'buffer-offer-save 'permanent-local t)
Roland McGrath's avatar
Roland McGrath committed
153

154
(defcustom find-file-existing-other-name t
155
  "Non-nil means find a file under alternative names, in existing buffers.
156
This means if any existing buffer is visiting the file you want
157 158 159
under another name, you get the existing buffer instead of a new buffer."
  :type 'boolean
  :group 'find-file)
160

161
(defcustom find-file-visit-truename nil
162
  "Non-nil means visit a file under its truename.
163
The truename of a file is found by chasing all links
164 165 166
both at the file level and at the levels of the containing directories."
  :type 'boolean
  :group 'find-file)
167
(put 'find-file-visit-truename 'safe-local-variable 'booleanp)
168

169
(defcustom revert-without-query nil
170
  "Specify which files should be reverted without query.
171 172
The value is a list of regular expressions.
If the file name matches one of these regular expressions,
173
then `revert-buffer' reverts the file without querying
174
if the file has changed on disk and you have not edited the buffer."
175
  :type '(repeat regexp)
176
  :group 'find-file)
177

178 179 180 181 182 183 184 185
(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)

186
(defvar buffer-file-numbers-unique (not (memq system-type '(windows-nt)))
187
  "Non-nil means that `buffer-file-number' uniquely identifies files.")
188

189 190 191 192
(defvar buffer-file-read-only nil
  "Non-nil if visited file was read-only when visited.")
(make-variable-buffer-local 'buffer-file-read-only)

193
(defcustom small-temporary-file-directory
194 195 196 197
  (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
198 199
have fast storage with limited space, such as a RAM disk."
  :group 'files
200
  :initialize 'custom-initialize-delay
201
  :type '(choice (const nil) directory))
202 203

;; The system null device. (Should reference NULL_DEVICE from C.)
204
(defvar null-device (purecopy "/dev/null") "The system null device.")
205

206 207
(declare-function msdos-long-file-names "msdos.c")
(declare-function w32-long-file-name "w32proc.c")
Dan Nicolaescu's avatar
Dan Nicolaescu committed
208 209 210 211
(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))
Eli Zaretskii's avatar
Eli Zaretskii committed
212
(declare-function dosified-file-name "dos-fns" (file-name))
Dan Nicolaescu's avatar
Dan Nicolaescu committed
213

214 215
(defvar file-name-invalid-regexp
  (cond ((and (eq system-type 'ms-dos) (not (msdos-long-file-names)))
216
	 (purecopy
217
	 (concat "^\\([^A-Z[-`a-z]\\|..+\\)?:\\|" ; colon except after drive
218
		 "[+, ;=|<>\"?*]\\|\\[\\|\\]\\|"  ; invalid characters
219
		 "[\000-\037]\\|"		  ; control characters
220
		 "\\(/\\.\\.?[^/]\\)\\|"	  ; leading dots
221
		 "\\(/[^/.]+\\.[^/.]*\\.\\)")))	  ; more than a single dot
Juanma Barranquero's avatar
Juanma Barranquero committed
222
	((memq system-type '(ms-dos windows-nt cygwin))
223
	 (purecopy
224
	 (concat "^\\([^A-Z[-`a-z]\\|..+\\)?:\\|" ; colon except after drive
225 226
		 "[|<>\"?*\000-\037]")))		  ; invalid characters
	(t (purecopy "[\000]")))
227 228
  "Regexp recognizing file names which aren't allowed by the filesystem.")

229
(defcustom file-precious-flag nil
230
  "Non-nil means protect against I/O errors while saving files.
Karl Heuer's avatar
Karl Heuer committed
231
Some modes set this non-nil in particular buffers.
232 233 234 235 236 237 238

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
239
Yet, at the same time, saving a precious file
240 241 242
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
243
file is being saved is not writable, Emacs may ignore a non-nil value
Karl Fogel's avatar
Karl Fogel committed
244 245 246
of `file-precious-flag' and write directly into the file.

See also: `break-hardlink-on-save'."
247 248
  :type 'boolean
  :group 'backup)
Roland McGrath's avatar
Roland McGrath committed
249

Karl Fogel's avatar
Karl Fogel committed
250 251
(defcustom break-hardlink-on-save nil
  "Non-nil means when saving a file that exists under several names
252
\(i.e., has multiple hardlinks), break the hardlink associated with
Karl Fogel's avatar
Karl Fogel committed
253 254 255 256 257 258 259
`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
260
itself writable, then error instead of saving in some
Karl Fogel's avatar
Karl Fogel committed
261 262 263 264
hardlink-nonbreaking way.

See also `backup-by-copying' and `backup-by-copying-when-linked'."
  :type 'boolean
265 266
  :group 'files
  :version "23.1")
Karl Fogel's avatar
Karl Fogel committed
267

268
(defcustom version-control nil
269
  "Control use of version numbers for backup files.
270 271 272
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."
273 274 275
  :type '(choice (const :tag "Never" never)
		 (const :tag "If existing" nil)
		 (other :tag "Always" t))
276 277
  :group 'backup
  :group 'vc)
278
(put 'version-control 'safe-local-variable
279
     (lambda (x) (or (booleanp x) (equal x 'never))))
280 281

(defcustom dired-kept-versions 2
282
  "When cleaning directory, number of versions to keep."
283 284 285 286 287
  :type 'integer
  :group 'backup
  :group 'dired)

(defcustom delete-old-versions nil
288
  "If t, delete excess backup versions silently.
289 290 291
If nil, ask confirmation.  Any other value prevents any trimming."
  :type '(choice (const :tag "Delete" t)
		 (const :tag "Ask" nil)
292
		 (other :tag "Leave" other))
293 294 295
  :group 'backup)

(defcustom kept-old-versions 2
296
  "Number of oldest versions to keep when a new numbered backup is made."
297 298
  :type 'integer
  :group 'backup)
299
(put 'kept-old-versions 'safe-local-variable 'integerp)
300 301

(defcustom kept-new-versions 2
302
  "Number of newest versions to keep when a new numbered backup is made.
303 304 305
Includes the new backup.  Must be > 0"
  :type 'integer
  :group 'backup)
306
(put 'kept-new-versions 'safe-local-variable 'integerp)
Roland McGrath's avatar
Roland McGrath committed
307

308
(defcustom require-final-newline nil
309
  "Whether to add a newline automatically at the end of the file.
310 311 312 313 314

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.
315
A value of nil means don't add newlines.
316 317 318 319 320 321

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)
322
		 (const :tag "Don't add newlines" nil)
323
		 (other :tag "Ask each time" ask))
324
  :group 'editing-basics)
Roland McGrath's avatar
Roland McGrath committed
325

326
(defcustom mode-require-final-newline t
327
  "Whether to add a newline at end of file, in certain major modes.
328
Those modes set `require-final-newline' to this value when you enable them.
329
They do so because they are often used for files that are supposed
330 331 332 333 334
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.
335 336
Any other non-nil value means ask user whether to add a newline, when saving.

337 338 339 340
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."
341 342 343
  :type '(choice (const :tag "When visiting" visit)
		 (const :tag "When saving" t)
		 (const :tag "When visiting or saving" visit-save)
344 345
		 (const :tag "Don't add newlines" nil)
		 (other :tag "Ask each time" ask))
346
  :group 'editing-basics
347
  :version "22.1")
348

349
(defcustom auto-save-default t
350
  "Non-nil says by default do auto-saving of every file-visiting buffer."
351 352
  :type 'boolean
  :group 'auto-save)
Roland McGrath's avatar
Roland McGrath committed
353

André Spiegel's avatar
André Spiegel committed
354
(defcustom auto-save-file-name-transforms
355
  `(("\\`/[^/]*:\\([^/]*/\\)*\\([^/]*\\)\\'"
356 357
     ;; Don't put "\\2" inside expand-file-name, since it will be
     ;; transformed to "/2" on DOS/Windows.
358
     ,(concat temporary-file-directory "\\2") t))
359
  "Transforms to apply to buffer file name before making auto-save file name.
360
Each transform is a list (REGEXP REPLACEMENT UNIQUIFY):
André Spiegel's avatar
André Spiegel committed
361 362 363
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.
364
If the optional element UNIQUIFY is non-nil, the auto-save file name is
365
constructed by taking the directory part of the replaced file-name,
366 367 368 369
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
370 371 372 373
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.

374 375
The default value is set up to put the auto-save file into the
temporary directory (see the variable `temporary-file-directory') for
376 377 378 379
editing a remote file.

On MS-DOS filesystems without long names this variable is always
ignored."
André Spiegel's avatar
André Spiegel committed
380
  :group 'auto-save
381 382
  :type '(repeat (list (string :tag "Regexp") (string :tag "Replacement")
					   (boolean :tag "Uniquify")))
383
  :initialize 'custom-initialize-delay
André Spiegel's avatar
André Spiegel committed
384 385
  :version "21.1")

386
(defcustom save-abbrevs t
387
  "Non-nil means save word abbrevs too when files are saved.
388 389
If `silently', don't ask the user before saving."
  :type '(choice (const t) (const nil) (const silently))
390
  :group 'abbrev)
Roland McGrath's avatar
Roland McGrath committed
391

392
(defcustom find-file-run-dired t
393
  "Non-nil means allow `find-file' to visit directories.
André Spiegel's avatar
André Spiegel committed
394
To visit the directory, `find-file' runs `find-directory-functions'."
395 396
  :type 'boolean
  :group 'find-file)
Roland McGrath's avatar
Roland McGrath committed
397

André Spiegel's avatar
André Spiegel committed
398
(defcustom find-directory-functions '(cvs-dired-noselect dired-noselect)
399
  "List of functions to try in sequence to visit a directory.
André Spiegel's avatar
André Spiegel committed
400 401 402 403 404
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)

405 406 407 408 409 410 411 412
;; FIXME: also add a hook for `(thing-at-point 'filename)'
(defcustom file-name-at-point-functions '(ffap-guess-file-name-at-point)
  "List of functions to try in sequence to get a file name at point.
Each function should return either nil or a file name found at the
location of point in the current buffer."
  :type '(hook :options (ffap-guess-file-name-at-point))
  :group 'find-file)

413 414
;;;It is not useful to make this a local variable.
;;;(put 'find-file-not-found-hooks 'permanent-local t)
415 416
(define-obsolete-variable-alias 'find-file-not-found-hooks
    'find-file-not-found-functions "22.1")
Stefan Monnier's avatar
Stefan Monnier committed
417
(defvar find-file-not-found-functions nil
Roland McGrath's avatar
Roland McGrath committed
418 419
  "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
420
Variable `buffer-file-name' is already set up.
Roland McGrath's avatar
Roland McGrath committed
421 422
The functions are called in the order given until one of them returns non-nil.")

423 424
;;;It is not useful to make this a local variable.
;;;(put 'find-file-hooks 'permanent-local t)
425
(define-obsolete-variable-alias 'find-file-hooks 'find-file-hook "22.1")
Dave Love's avatar
Dave Love committed
426
(defcustom find-file-hook nil
Roland McGrath's avatar
Roland McGrath committed
427 428
  "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
429 430 431 432
functions are called."
  :group 'find-file
  :type 'hook
  :options '(auto-insert)
433
  :version "22.1")
Roland McGrath's avatar
Roland McGrath committed
434

435
(define-obsolete-variable-alias 'write-file-hooks 'write-file-functions "22.1")
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
451 452 453
(put 'write-file-functions 'permanent-local t)

(defvar local-write-file-hooks nil)
454 455
(make-variable-buffer-local 'local-write-file-hooks)
(put 'local-write-file-hooks 'permanent-local t)
456
(make-obsolete-variable 'local-write-file-hooks 'write-file-functions "22.1")
Jim Blandy's avatar
Jim Blandy committed
457

458 459
(define-obsolete-variable-alias 'write-contents-hooks
    'write-contents-functions "22.1")
Stefan Monnier's avatar
Stefan Monnier committed
460
(defvar write-contents-functions nil
Jim Blandy's avatar
Jim Blandy committed
461 462
  "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
463 464
and the rest are not called and neither are the functions in
`write-file-functions'.
465 466 467 468

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
469 470
major mode does clear it.

471 472 473 474 475
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
476
(make-variable-buffer-local 'write-contents-functions)
Roland McGrath's avatar
Roland McGrath committed
477

478
(defcustom enable-local-variables t
479
  "Control use of local variables in files you visit.
480
The value can be t, nil, :safe, :all, or something else.
481 482

A value of t means file local variables specifications are obeyed
483 484
if all the specified variable values are safe; if any values are
not safe, Emacs queries you, once, whether to set them all.
485 486 487
\(When you say yes to certain values, they are remembered as safe.)

:safe means set the safe variables, and ignore the rest.
488 489
:all means set all variables, whether safe or not.
 (Don't set it permanently to :all.)
490
A value of nil means always ignore the file local variables.
491 492

Any other value means always query you once whether to set them all.
493 494
\(When you say yes to certain values, they are remembered as safe, but
this has no effect when `enable-local-variables' is \"something else\".)
495

496 497
This variable also controls use of major modes specified in
a -*- line.
Roland McGrath's avatar
Roland McGrath committed
498

499 500 501
The command \\[normal-mode], when used interactively,
always obeys file local variable specifications and the -*- line,
and ignores this variable."
502
  :risky t
503
  :type '(choice (const :tag "Query Unsafe" t)
504
		 (const :tag "Safe Only" :safe)
505
		 (const :tag "Do all" :all)
506
		 (const :tag "Ignore" nil)
507
		 (other :tag "Query" other))
508
  :group 'find-file)
Roland McGrath's avatar
Roland McGrath committed
509

510 511 512 513 514
(defvar enable-dir-local-variables t
  "Non-nil means enable use of directory-local variables.
Some modes may wish to set this to nil to prevent directory-local
settings being applied, but still respect file-local ones.")

Glenn Morris's avatar
Glenn Morris committed
515 516 517 518 519 520 521 522 523 524 525 526 527 528 529 530 531 532 533 534 535 536
;; This is an odd variable IMO.
;; You might wonder why it is needed, when we could just do:
;; (set (make-local-variable 'enable-local-variables) nil)
;; These two are not precisely the same.
;; Setting this variable does not cause -*- mode settings to be
;; ignored, whereas setting enable-local-variables does.
;; Only three places in Emacs use this variable: tar and arc modes,
;; and rmail.  The first two don't need it.  They already use
;; inhibit-local-variables-regexps, which is probably enough, and
;; could also just set enable-local-variables locally to nil.
;; Them setting it has the side-effect that dir-locals cannot apply to
;; eg tar files (?).  FIXME Is this appropriate?
;; AFAICS, rmail is the only thing that needs this, and the only
;; reason it uses it is for BABYL files (which are obsolete).
;; These contain "-*- rmail -*-" in the first line, which rmail wants
;; to respect, so that find-file on a BABYL file will switch to
;; rmail-mode automatically (this is nice, but hardly essential,
;; since most people are used to explicitly running a command to
;; access their mail; M-x gnus etc).  Rmail files may happen to
;; contain Local Variables sections in messages, which Rmail wants to
;; ignore.  So AFAICS the only reason this variable exists is for a
;; minor convenience feature for handling of an obsolete Rmail file format.
537 538
(defvar local-enable-local-variables t
  "Like `enable-local-variables' but meant for buffer-local bindings.
539
The meaningful values are nil and non-nil.  The default is non-nil.
540
If a major mode sets this to nil, buffer-locally, then any local
Glenn Morris's avatar
Glenn Morris committed
541
variables list in a file visited in that mode will be ignored.
542

Glenn Morris's avatar
Glenn Morris committed
543 544
This variable does not affect the use of major modes specified
in a -*- line.")
545

546
(defcustom enable-local-eval 'maybe
547
  "Control processing of the \"variable\" `eval' in a file's local variables.
548
The value can be t, nil or something else.
549
A value of t means obey `eval' variables.
550
A value of nil means ignore them; anything else means query."
551
  :risky t
552 553
  :type '(choice (const :tag "Obey" t)
		 (const :tag "Ignore" nil)
554
		 (other :tag "Query" other))
555
  :group 'find-file)
Roland McGrath's avatar
Roland McGrath committed
556 557 558

;; Avoid losing in versions where CLASH_DETECTION is disabled.
(or (fboundp 'lock-buffer)
559
    (defalias 'lock-buffer 'ignore))
Roland McGrath's avatar
Roland McGrath committed
560
(or (fboundp 'unlock-buffer)
561
    (defalias 'unlock-buffer 'ignore))
562 563
(or (fboundp 'file-locked-p)
    (defalias 'file-locked-p 'ignore))
564

565
(defcustom view-read-only nil
566
  "Non-nil means buffers visiting files read-only do so in view mode.
567 568 569 570
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]."
571 572
  :type 'boolean
  :group 'view)
573

574
(defvar file-name-history nil
575 576 577 578
  "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.")
579

580
(put 'ange-ftp-completion-hook-function 'safe-magic t)
581
(defun ange-ftp-completion-hook-function (op &rest args)
André Spiegel's avatar
André Spiegel committed
582 583 584 585
  "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.
586 587
  (if (memq op '(file-name-completion file-name-all-completions))
      (apply 'ange-ftp-hook-function op args)
588 589 590 591 592
    (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))
593
      (apply op args))))
594

595 596 597
(declare-function dos-convert-standard-filename "dos-fns.el" (filename))
(declare-function w32-convert-standard-filename "w32-fns.el" (filename))

598
(defun convert-standard-filename (filename)
599
  "Convert a standard file's name to something suitable for the OS.
600 601 602
This means to guarantee valid names and perhaps to canonicalize
certain patterns.

603 604 605 606
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.

607 608
This function's standard definition is trivial; it just returns
the argument.  However, on Windows and DOS, replace invalid
609 610 611
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
612 613 614
`w32-shell-dos-semantics').

See Info node `(elisp)Standard File Names' for more details."
615 616 617 618 619 620 621 622 623 624 625 626 627 628
  (cond
   ((eq system-type 'cygwin)
    (let ((name (copy-sequence filename))
	  (start 0))
      ;; Replace invalid filename characters with !
      (while (string-match "[?*:<>|\"\000-\037]" name start)
	(aset name (match-beginning 0) ?!)
	(setq start (match-end 0)))
      name))
   ((eq system-type 'windows-nt)
    (w32-convert-standard-filename filename))
   ((eq system-type 'ms-dos)
    (dos-convert-standard-filename filename))
   (t filename)))
629 630 631 632

(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.
633 634
Default name to DEFAULT-DIRNAME if user exits with the same
non-empty string that was inserted by this function.
635 636
 (If DEFAULT-DIRNAME is omitted, DIR combined with INITIAL is used,
  or just DIR if INITIAL is nil.)
637 638 639
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.)
640 641 642
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.
643 644
DIR should be an absolute directory name.  It defaults to
the value of `default-directory'."
645 646
  (unless dir
    (setq dir default-directory))
647
  (read-file-name prompt dir (or default-dirname
648 649 650
				 (if initial (expand-file-name initial dir)
				   dir))
		  mustmatch initial
651 652
		  'file-directory-p))

Roland McGrath's avatar
Roland McGrath committed
653 654 655 656 657 658

(defun pwd ()
  "Show the current default directory."
  (interactive nil)
  (message "Directory %s" default-directory))

659 660
(defvar cd-path nil
  "Value of the CDPATH environment variable, as a list.
661
Not actually set up until the first time you use it.")
662

663
(defun parse-colon-path (search-path)
664
  "Explode a search path into a list of directory names.
665 666
Directories are separated by `path-separator' (which is colon in
GNU and Unix systems).  Substitute environment variables into the
667 668 669
resulting list of directory names.  For an empty path element (i.e.,
a leading or trailing separator, or two adjacent separators), return
nil (meaning `default-directory') as the associated list element."
670 671
  (when (stringp search-path)
    (mapcar (lambda (f)
672 673 674
	      (if (equal "" f) nil
		(substitute-in-file-name (file-name-as-directory f))))
	    (split-string search-path path-separator))))
675 676

(defun cd-absolute (dir)
677
  "Change current directory to given absolute file name DIR."
678 679
  ;; Put the name into directory syntax now,
  ;; because otherwise expand-file-name may give some bad results.
Dan Nicolaescu's avatar
Dan Nicolaescu committed
680
  (setq dir (file-name-as-directory dir))
681 682 683 684 685 686
  ;; 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
687
  (if (not (file-directory-p dir))
688 689
      (if (file-exists-p dir)
	  (error "%s is not a directory" dir)
690
	(error "%s: no such directory" dir))
691 692 693
    (unless (file-executable-p dir)
      (error "Cannot cd to %s:  Permission denied" dir))
    (setq default-directory dir)
694
    (setq list-buffers-directory dir)))
Roland McGrath's avatar
Roland McGrath committed
695

696 697
(defun cd (dir)
  "Make DIR become the current buffer's default directory.
698 699
If your environment includes a `CDPATH' variable, try each one of
that list of directories (separated by occurrences of
700 701
`path-separator') when resolving a relative directory name.
The path separator is colon in GNU and GNU-like systems."
702
  (interactive
703 704 705 706 707 708 709 710 711 712 713 714 715 716 717 718 719 720 721 722 723 724 725 726 727 728 729 730 731 732 733
   (list
    ;; FIXME: There's a subtle bug in the completion below.  Seems linked
    ;; to a fundamental difficulty of implementing `predicate' correctly.
    ;; The manifestation is that TAB may list non-directories in the case where
    ;; those files also correspond to valid directories (if your cd-path is (A/
    ;; B/) and you have A/a a file and B/a a directory, then both `a' and `a/'
    ;; will be listed as valid completions).
    ;; This is because `a' (listed because of A/a) is indeed a valid choice
    ;; (which will lead to the use of B/a).
    (minibuffer-with-setup-hook
        (lambda ()
          (setq minibuffer-completion-table
                (apply-partially #'locate-file-completion-table
                                 cd-path nil))
          (setq minibuffer-completion-predicate
                (lambda (dir)
                  (locate-file dir cd-path nil
                               (lambda (f) (and (file-directory-p f) 'dir-ok))))))
      (unless cd-path
        (setq cd-path (or (parse-colon-path (getenv "CDPATH"))
                          (list "./"))))
      (read-directory-name "Change default directory: "
                           default-directory default-directory
                           t))))
  (unless cd-path
    (setq cd-path (or (parse-colon-path (getenv "CDPATH"))
                      (list "./"))))
  (cd-absolute
   (or (locate-file dir cd-path nil
                    (lambda (f) (and (file-directory-p f) 'dir-ok)))
       (error "No such directory found via CDPATH environment variable"))))
734

Roland McGrath's avatar
Roland McGrath committed
735 736
(defun load-file (file)
  "Load the Lisp file named FILE."
737 738
  ;; This is a case where .elc makes a lot of sense.
  (interactive (list (let ((completion-ignored-extensions
Dave Love's avatar
Dave Love committed
739
			    (remove ".elc" completion-ignored-extensions)))
740
		       (read-file-name "Load file: " nil nil 'lambda))))
741
  (load (expand-file-name file) nil nil t))
Roland McGrath's avatar
Roland McGrath committed
742

Stefan Monnier's avatar
Stefan Monnier committed
743 744
(defun locate-file (filename path &optional suffixes predicate)
  "Search for FILENAME through PATH.
Eli Zaretskii's avatar
Eli Zaretskii committed
745 746 747 748
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
749 750
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
751
Use '(\"/\") to disable PATH search, but still try the suffixes in SUFFIXES.
Stefan Monnier's avatar
Stefan Monnier committed
752
If non-nil, PREDICATE is used instead of `file-readable-p'.
753 754 755 756

This function will normally skip directories, so if you want it to find
directories, make sure the PREDICATE function returns `dir-ok' for them.

Richard M. Stallman's avatar
Richard M. Stallman committed
757 758 759 760 761
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
762 763 764 765 766 767 768 769 770
  (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))

771 772
(defun locate-file-completion-table (dirs suffixes string pred action)
  "Do completion for file names passed to `locate-file'."
773 774
  (cond
   ((file-name-absolute-p string)
775 776 777 778
    ;; 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))
779 780
   ((eq (car-safe action) 'boundaries)
    (let ((suffix (cdr action)))
781 782 783 784
      `(boundaries
        ,(length (file-name-directory string))
        ,@(let ((x (file-name-directory suffix)))
            (if x (1- (length x)) (length suffix))))))
785
   (t
786 787 788 789 790 791 792 793 794 795 796
    (let ((names '())
          ;; If we have files like "foo.el" and "foo.elc", we could load one of
          ;; them with "foo.el", "foo.elc", or "foo", where just "foo" is the
          ;; preferred way.  So if we list all 3, that gives a lot of redundant
          ;; entries for the poor soul looking just for "foo".  OTOH, sometimes
          ;; the user does want to pay attention to the extension.  We try to
          ;; diffuse this tension by stripping the suffix, except when the
          ;; result is a single element (i.e. usually we only list "foo" unless
          ;; it's the only remaining element in the list, in which case we do
          ;; list "foo", "foo.elc" and "foo.el").
          (fullnames '())
797
	  (suffix (concat (regexp-opt suffixes t) "\\'"))
798 799
	  (string-dir (file-name-directory string))
          (string-file (file-name-nondirectory string)))
800
      (dolist (dir dirs)
801 802 803 804 805 806 807 808 809 810 811 812 813
        (unless dir
          (setq dir default-directory))
        (if string-dir (setq dir (expand-file-name string-dir dir)))
        (when (file-directory-p dir)
          (dolist (file (file-name-all-completions
                         string-file dir))
            (if (not (string-match suffix file))
                (push file names)
              (push file fullnames)
              (push (substring file 0 (match-beginning 0)) names)))))
      ;; Switching from names to names+fullnames creates a non-monotonicity
      ;; which can cause problems with things like partial-completion.
      ;; To minimize the problem, filter out completion-regexp-list, so that
814 815 816 817
      ;; M-x load-library RET t/x.e TAB finds some files.  Also remove elements
      ;; from `names' which only matched `string' when they still had
      ;; their suffix.
      (setq names (all-completions string names))
818 819 820 821 822 823 824
      ;; Remove duplicates of the first element, so that we can easily check
      ;; if `names' really only contains a single element.
      (when (cdr names) (setcdr names (delete (car names) (cdr names))))
      (unless (cdr names)
        ;; There's no more than one matching non-suffixed element, so expand
        ;; the list by adding the suffixed elements as well.
        (setq names (nconc names fullnames)))
825 826
      (completion-table-with-context
       string-dir names string-file pred action)))))
827 828 829 830

(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)."
831
  (declare (obsolete locate-file-completion-table "23.1"))
832 833 834
  (locate-file-completion-table (car path-and-suffixes)
                                (cdr path-and-suffixes)
                                string nil action))
835

836
(defvar locate-dominating-stop-dir-regexp
837
  (purecopy "\\`\\(?:[\\/][\\/][^\\/]+[\\/]\\|/\\(?:net\\|afs\\|\\.\\.\\.\\)/\\)\\'")
838 839 840 841 842
  "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
843 844
special files in directories in which filenames are interpreted as hostnames,
or mount points potentially requiring authentication as a different user.")
845 846 847 848 849 850 851 852 853 854 855 856 857 858 859 860 861 862 863 864 865 866 867 868 869 870 871 872 873 874 875

;; (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)))