files.el 116 KB
Newer Older
Eric S. Raymond's avatar
Eric S. Raymond committed
1 2
;;; files.el --- file input and output commands for Emacs

Richard M. Stallman's avatar
Richard M. Stallman committed
3 4
;; Copyright (C) 1985, 86, 87, 92, 93,
;;		 94, 95, 1996 Free Software Foundation, Inc.
Roland McGrath's avatar
Roland McGrath committed
5

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

Roland McGrath's avatar
Roland McGrath committed
8 9 10 11
;; 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
Eric S. Raymond's avatar
Eric S. Raymond committed
12
;; the Free Software Foundation; either version 2, or (at your option)
Roland McGrath's avatar
Roland McGrath committed
13 14 15 16 17 18 19 20
;; 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
21 22 23
;; along with GNU Emacs; see the file COPYING.  If not, write to the
;; Free Software Foundation, Inc., 59 Temple Place - Suite 330,
;; Boston, MA 02111-1307, USA.
Roland McGrath's avatar
Roland McGrath committed
24

25 26 27 28 29 30
;;; 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
31 32
;;; Code:

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 43 44 45 46 47


(defcustom delete-auto-save-files t
  "*Non-nil means delete auto-save file when a buffer is saved or killed."
  :type 'boolean
  :group 'auto-save)

(defcustom directory-abbrev-alist
Roland McGrath's avatar
Roland McGrath committed
48 49 50 51 52 53 54
  nil
  "*Alist of abbreviations for file directories.
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.
*Every* FROM string should start with `^'.

55 56 57
Do not use `~' in the TO strings.
They should be ordinary absolute directory names.

Roland McGrath's avatar
Roland McGrath committed
58 59
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
60 61 62 63 64 65 66
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
67 68

;;; Turn off backup files on VMS since it has version numbers.
69
(defcustom make-backup-files (not (eq system-type 'vax-vms))
70
  "*Non-nil means make a backup of a file the first time it is saved.
Roland McGrath's avatar
Roland McGrath committed
71 72 73 74 75 76 77 78 79 80 81 82 83 84
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
`backup-by-copying', `backup-by-copying-when-linked' and
85 86 87
`backup-by-copying-when-mismatch'.  See also `backup-inhibited'."
  :type 'boolean
  :group 'backup)
Roland McGrath's avatar
Roland McGrath committed
88 89 90 91

;; Do this so that local variables based on the file name
;; are not overridden by the major mode.
(defvar backup-inhibited nil
92 93 94
  "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
95 96
(put 'backup-inhibited 'permanent-local t)

97
(defcustom backup-by-copying nil
Roland McGrath's avatar
Roland McGrath committed
98
 "*Non-nil means always use copying to create backup files.
99 100 101
See documentation of variable `make-backup-files'."
 :type 'boolean
 :group 'backup)
Roland McGrath's avatar
Roland McGrath committed
102

103
(defcustom backup-by-copying-when-linked nil
Roland McGrath's avatar
Roland McGrath committed
104 105
 "*Non-nil means use copying to create backups for files with multiple names.
This causes the alternate names to refer to the latest version as edited.
106 107 108
This variable is relevant only if `backup-by-copying' is nil."
 :type 'boolean
 :group 'backup)
Roland McGrath's avatar
Roland McGrath committed
109

110
(defcustom backup-by-copying-when-mismatch nil
Roland McGrath's avatar
Roland McGrath committed
111 112 113 114 115
  "*Non-nil means create backups by copying if this preserves owner or group.
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.
116 117 118
This variable is relevant only if `backup-by-copying' is nil."
  :type 'boolean
  :group 'backup)
Roland McGrath's avatar
Roland McGrath committed
119 120 121 122 123 124 125 126

(defvar backup-enable-predicate
  '(lambda (name)
     (or (< (length name) 5)
	 (not (string-equal "/tmp/" (substring name 0 5)))))
  "Predicate that looks at a file name and decides whether to make backups.
Called with an absolute file name as argument, it returns t to enable backup.")

127
(defcustom buffer-offer-save nil
Roland McGrath's avatar
Roland McGrath committed
128 129
  "*Non-nil in a buffer means offer to save the buffer on exit
even if the buffer is not visiting a file.
130 131 132
Automatically local in all buffers."
  :type 'boolean
  :group 'backup)
Roland McGrath's avatar
Roland McGrath committed
133 134
(make-variable-buffer-local 'buffer-offer-save)

135
(defcustom find-file-existing-other-name t
136 137
  "*Non-nil means find a file under alternative names, in existing buffers.
This means if any existing buffer is visiting the file you want
138 139 140
under another name, you get the existing buffer instead of a new buffer."
  :type 'boolean
  :group 'find-file)
141

142
(defcustom find-file-visit-truename nil
143 144
  "*Non-nil means visit a file under its truename.
The truename of a file is found by chasing all links
145 146 147
both at the file level and at the levels of the containing directories."
  :type 'boolean
  :group 'find-file)
148

149
(defcustom revert-without-query
150
  nil
151 152 153
  "*Specify which files should be reverted without query.
The value is a list of regular expressions.
If the file name matches one of these regular expressions,
154
then `revert-buffer' reverts the file without querying
155 156 157
if the file has changed on disk and you have not edited the buffer."
  :type 'boolean
  :group 'find-file)
158

159 160 161 162 163 164 165 166
(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)

167 168 169
(defvar buffer-file-numbers-unique (not (memq system-type '(windows-nt)))
  "Non-nil means that buffer-file-number uniquely identifies files.")

170
(defcustom file-precious-flag nil
Roland McGrath's avatar
Roland McGrath committed
171
  "*Non-nil means protect against I/O errors while saving files.
Karl Heuer's avatar
Karl Heuer committed
172
Some modes set this non-nil in particular buffers.
173 174 175 176 177 178 179

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
180
Yet, at the same time, saving a precious file
181 182 183
breaks any hard links between it and other files."
  :type 'boolean
  :group 'backup)
Roland McGrath's avatar
Roland McGrath committed
184

185
(defcustom version-control nil
Roland McGrath's avatar
Roland McGrath committed
186 187 188
  "*Control use of version numbers for backup files.
t means make numeric backup versions unconditionally.
nil means make them for files that have some already.
189 190 191 192 193 194 195 196 197 198 199 200
`never' means do not make them."
  :type 'boolean
  :group 'backup
  :group 'vc)

(defcustom dired-kept-versions 2
  "*When cleaning directory, number of versions to keep."
  :type 'integer
  :group 'backup
  :group 'dired)

(defcustom delete-old-versions nil
201
  "*If t, delete excess backup versions silently.
202 203 204 205 206 207 208 209 210 211 212 213
If nil, ask confirmation.  Any other value prevents any trimming."
  :type '(choice (const :tag "Delete" t)
		 (const :tag "Ask" nil)
		 (sexp :tag "Leave" :format "%t\n" other))
  :group 'backup)

(defcustom kept-old-versions 2
  "*Number of oldest versions to keep when a new numbered backup is made."
  :type 'integer
  :group 'backup)

(defcustom kept-new-versions 2
Roland McGrath's avatar
Roland McGrath committed
214
  "*Number of newest versions to keep when a new numbered backup is made.
215 216 217
Includes the new backup.  Must be > 0"
  :type 'integer
  :group 'backup)
Roland McGrath's avatar
Roland McGrath committed
218

219
(defcustom require-final-newline nil
Roland McGrath's avatar
Roland McGrath committed
220 221
  "*Value of t says silently ensure a file ends in a newline when it is saved.
Non-nil but not t says ask user whether to add a newline when there isn't one.
222
nil means don't add newlines."
223 224 225
  :type '(choice (const :tag "Off" nil)
		 (const :tag "Add" t)
		 (sexp :tag "Ask" :format "%t\n" ask))
226
  :group 'editing-basics)
Roland McGrath's avatar
Roland McGrath committed
227

228 229 230 231
(defcustom auto-save-default t
  "*Non-nil says by default do auto-saving of every file-visiting buffer."
  :type 'boolean
  :group 'auto-save)
Roland McGrath's avatar
Roland McGrath committed
232

233
(defcustom auto-save-visited-file-name nil
Roland McGrath's avatar
Roland McGrath committed
234
  "*Non-nil says auto-save a buffer in the file it is visiting, when practical.
235 236 237
Normally auto-save files are written under other names."
  :type 'boolean
  :group 'auto-save)
Roland McGrath's avatar
Roland McGrath committed
238

239
(defcustom save-abbrevs nil
Roland McGrath's avatar
Roland McGrath committed
240
  "*Non-nil means save word abbrevs too when files are saved.
241 242 243
Loading an abbrev file sets this to t."
  :type 'boolean
  :group 'abbrev)
Roland McGrath's avatar
Roland McGrath committed
244

245 246 247 248
(defcustom find-file-run-dired t
  "*Non-nil says run dired if `find-file' is given the name of a directory."
  :type 'boolean
  :group 'find-file)
Roland McGrath's avatar
Roland McGrath committed
249

250 251
;;;It is not useful to make this a local variable.
;;;(put 'find-file-not-found-hooks 'permanent-local t)
Roland McGrath's avatar
Roland McGrath committed
252 253 254 255 256 257
(defvar find-file-not-found-hooks nil
  "List of functions to be called for `find-file' on nonexistent file.
These functions are called as soon as the error is detected.
`buffer-file-name' is already set up.
The functions are called in the order given until one of them returns non-nil.")

258 259
;;;It is not useful to make this a local variable.
;;;(put 'find-file-hooks 'permanent-local t)
Roland McGrath's avatar
Roland McGrath committed
260 261 262 263 264 265 266 267
(defvar find-file-hooks nil
  "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
functions are called.")

(defvar write-file-hooks nil
  "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
268 269 270
and the rest are not called.
These hooks are considered to pertain to the visited file.
So this list is cleared if you change the visited file name.
271 272 273

Don't make this variable buffer-local; instead, use `local-write-file-hooks'.
See also `write-contents-hooks'.")
274 275
;;; However, in case someone does make it local...
(put 'write-file-hooks 'permanent-local t)
276 277 278 279

(defvar local-write-file-hooks nil
  "Just like `write-file-hooks', except intended for per-buffer use.
The functions in this list are called before the ones in
280 281 282 283 284 285
`write-file-hooks'.

This variable is meant to be used for hooks that have to do with a
particular visited file.  Therefore, it is a permanent local, so that
changing the major mode does not clear it.  However, calling
`set-visited-file-name' does clear it.")
286 287
(make-variable-buffer-local 'local-write-file-hooks)
(put 'local-write-file-hooks 'permanent-local t)
Jim Blandy's avatar
Jim Blandy committed
288 289 290 291 292

(defvar write-contents-hooks nil
  "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
and the rest are not called.
293 294 295 296

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
297 298 299
major mode does clear it.

This variable automatically becomes buffer-local whenever it is set.
Karl Heuer's avatar
Karl Heuer committed
300
If you use `add-hook' to add elements to the list, use nil for the
301
LOCAL argument.
302

Jim Blandy's avatar
Jim Blandy committed
303
See also `write-file-hooks'.")
304
(make-variable-buffer-local 'write-contents-hooks)
Roland McGrath's avatar
Roland McGrath committed
305

306
(defcustom enable-local-variables t
307
  "*Control use of local variables in files you visit.
Roland McGrath's avatar
Roland McGrath committed
308
The value can be t, nil or something else.
309
A value of t means file local variables specifications are obeyed;
Roland McGrath's avatar
Roland McGrath committed
310 311
nil means they are ignored; anything else means query.

312
The command \\[normal-mode] always obeys file local variable
313 314 315 316 317
specifications and ignores this variable."
  :type '(choice (const :tag "Obey" t)
		 (const :tag "Ignore" nil)
		 (sexp :tag "Query" :format "%t\n" other))
  :group 'find-file)
Roland McGrath's avatar
Roland McGrath committed
318

319
(defcustom enable-local-eval 'maybe
320 321 322 323 324 325
  "*Control processing of the \"variable\" `eval' in a file's local variables.
The value can be t, nil or something else.
A value of t means obey `eval' variables;
nil means ignore them; anything else means query.

The command \\[normal-mode] always obeys local-variables lists
326 327 328 329 330
and ignores this variable."
  :type '(choice (const :tag "Obey" t)
		 (const :tag "Ignore" nil)
		 (sexp :tag "Query" :format "%t\n" other))
  :group 'find-file)
Roland McGrath's avatar
Roland McGrath committed
331 332 333

;; Avoid losing in versions where CLASH_DETECTION is disabled.
(or (fboundp 'lock-buffer)
334
    (defalias 'lock-buffer 'ignore))
Roland McGrath's avatar
Roland McGrath committed
335
(or (fboundp 'unlock-buffer)
336
    (defalias 'unlock-buffer 'ignore))
337 338
(or (fboundp 'file-locked-p)
    (defalias 'file-locked-p 'ignore))
339

340 341 342
(defvar view-read-only nil
  "*Non-nil means buffers visiting files read-only, do it in view mode.")

343 344 345 346 347 348 349
;; This hook function provides support for ange-ftp host name
;; completion.  It 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.
(defun ange-ftp-completion-hook-function (op &rest args)
  (if (memq op '(file-name-completion file-name-all-completions))
      (apply 'ange-ftp-hook-function op args)
350 351 352 353 354
    (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))
355
      (apply op args))))
356 357 358 359 360 361 362

(defun convert-standard-filename (filename)
  "Convert a standard file's name to something suitable for the current OS.
This function's standard definition is trivial; it just returns the argument.
However, on some systems, the function is redefined
with a definition that really does change some file names."
  filename)
Roland McGrath's avatar
Roland McGrath committed
363 364 365 366 367 368

(defun pwd ()
  "Show the current default directory."
  (interactive nil)
  (message "Directory %s" default-directory))

369 370 371 372
(defvar cd-path nil
  "Value of the CDPATH environment variable, as a list.
Not actually set up until the first time you you use it.")

373
(defvar path-separator ":"
374
  "Character used to separate directories in search paths.")
375

376
(defun parse-colon-path (cd-path)
377
  "Explode a colon-separated search path into a list of directory names."
378 379
  (and cd-path
       (let (cd-prefix cd-list (cd-start 0) cd-colon)
380 381
	 (setq cd-path (concat cd-path path-separator))
	 (while (setq cd-colon (string-match path-separator cd-path cd-start))
382
	   (setq cd-list
383
		 (nconc cd-list
384 385 386
			(list (if (= cd-start cd-colon)
				   nil
				(substitute-in-file-name
387 388
				 (file-name-as-directory
				  (substring cd-path cd-start cd-colon)))))))
389 390 391 392
	   (setq cd-start (+ cd-colon 1)))
	 cd-list)))

(defun cd-absolute (dir)
393
  "Change current directory to given absolute file name DIR."
394 395
  ;; Put the name into directory syntax now,
  ;; because otherwise expand-file-name may give some bad results.
Roland McGrath's avatar
Roland McGrath committed
396 397
  (if (not (eq system-type 'vax-vms))
      (setq dir (file-name-as-directory dir)))
398
  (setq dir (abbreviate-file-name (expand-file-name dir)))
Roland McGrath's avatar
Roland McGrath committed
399 400 401 402
  (if (not (file-directory-p dir))
      (error "%s is not a directory" dir)
    (if (file-executable-p dir)
	(setq default-directory dir)
403
      (error "Cannot cd to %s:  Permission denied" dir))))
Roland McGrath's avatar
Roland McGrath committed
404

405 406
(defun cd (dir)
  "Make DIR become the current buffer's default directory.
407 408
If your environment includes a `CDPATH' variable, try each one of that
colon-separated list of directories when resolving a relative directory name."
409 410
  (interactive
   (list (read-file-name "Change default directory: "
411 412 413
			 default-directory default-directory
			 (and (member cd-path '(nil ("./")))
			      (null (getenv "CDPATH"))))))
414 415 416 417 418 419 420 421 422 423 424 425 426 427 428 429
  (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
	       (mapcar
		(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"))))
430

Roland McGrath's avatar
Roland McGrath committed
431 432 433 434 435 436 437 438 439 440
(defun load-file (file)
  "Load the Lisp file named FILE."
  (interactive "fLoad file: ")
  (load (expand-file-name file) nil nil t))

(defun load-library (library)
  "Load the library named LIBRARY.
This is an interface to the function `load'."
  (interactive "sLoad library: ")
  (load library))
441

Karl Heuer's avatar
Karl Heuer committed
442
(defun file-local-copy (file &optional buffer)
443 444 445
  "Copy the file FILE into a temporary file on this machine.
Returns the name of the local copy, or nil, if FILE is directly
accessible."
446
  (let ((handler (find-file-name-handler file 'file-local-copy)))
447 448 449
    (if handler
	(funcall handler 'file-local-copy file)
      nil)))
450

451
(defun file-truename (filename &optional counter prev-dirs)
452 453 454
  "Return the truename of FILENAME, which should be absolute.
The truename of a file name is found by chasing symbolic links
both at the level of the file and at the level of the directories
455 456 457 458 459 460 461 462
containing it, until no links are left at any level.

The arguments COUNTER and PREV-DIRS are used only in recursive calls.
Do not specify them in other calls."
  ;; COUNTER can be a cons cell whose car is the count of how many more links
  ;; to chase before getting an error.
  ;; PREV-DIRS can be a cons cell whose car is an alist
  ;; of truenames we've just recently computed.
463 464 465

  ;; The last test looks dubious, maybe `+' is meant here?  --simon.
  (if (or (string= filename "") (string= filename "~")
466 467
	  (and (string= (substring filename 0 1) "~")
	       (string-match "~[^/]*" filename)))
468 469 470 471
      (progn
	(setq filename (expand-file-name filename))
	(if (string= filename "")
	    (setq filename "/"))))
472
  (or counter (setq counter (list 100)))
473 474 475 476 477 478 479 480 481
  (let (done
	;; For speed, remove the ange-ftp completion handler from the list.
	;; We know it's not needed here.
	;; For even more speed, do this only on the outermost call.
	(file-name-handler-alist
	 (if prev-dirs file-name-handler-alist
	   (let ((tem (copy-sequence file-name-handler-alist)))
	     (delq (rassq 'ange-ftp-completion-hook-function tem) tem)))))
    (or prev-dirs (setq prev-dirs (list nil)))
482 483 484 485 486 487 488 489 490 491 492 493
    ;; If this file directly leads to a link, process that iteratively
    ;; so that we don't use lots of stack.
    (while (not done)
      (setcar counter (1- (car counter)))
      (if (< (car counter) 0)
	  (error "Apparent cycle of symbolic links for %s" filename))
      (let ((handler (find-file-name-handler filename 'file-truename)))
	;; For file name that has a special handler, call handler.
	;; This is so that ange-ftp can save time by doing a no-op.
	(if handler
	    (setq filename (funcall handler 'file-truename filename)
		  done t)
494
	  (let ((dir (or (file-name-directory filename) default-directory))
495 496 497 498 499 500 501 502 503 504 505 506 507 508 509 510 511 512 513 514 515 516 517 518 519 520 521 522 523 524 525 526 527 528 529 530 531 532
		target dirfile)
	    ;; Get the truename of the directory.
	    (setq dirfile (directory-file-name dir))
	    ;; If these are equal, we have the (or a) root directory.
	    (or (string= dir dirfile)
		;; If this is the same dir we last got the truename for,
		;; save time--don't recalculate.
		(if (assoc dir (car prev-dirs))
		    (setq dir (cdr (assoc dir (car prev-dirs))))
		  (let ((old dir)
			(new (file-name-as-directory (file-truename dirfile counter prev-dirs))))
		    (setcar prev-dirs (cons (cons old new) (car prev-dirs)))
		    (setq dir new))))
	    (if (equal ".." (file-name-nondirectory filename))
		(setq filename
		      (directory-file-name (file-name-directory (directory-file-name dir)))
		      done t)
	      (if (equal "." (file-name-nondirectory filename))
		  (setq filename (directory-file-name dir)
			done t)
		;; Put it back on the file name.
		(setq filename (concat dir (file-name-nondirectory filename)))
		;; Is the file name the name of a link?
		(setq target (file-symlink-p filename))
		(if target
		    ;; Yes => chase that link, then start all over
		    ;; since the link may point to a directory name that uses links.
		    ;; We can't safely use expand-file-name here
		    ;; since target might look like foo/../bar where foo
		    ;; is itself a link.  Instead, we handle . and .. above.
		    (setq filename
			  (if (file-name-absolute-p target)
			      target
			    (concat dir target))
			  done nil)
		  ;; No, we are done!
		  (setq done t))))))))
    filename))
533

534 535 536 537 538 539
(defun file-chase-links (filename)
  "Chase links in FILENAME until a name that is not a link.
Does not examine containing directories for links,
unlike `file-truename'."
  (let (tem (count 100) (newname filename))
    (while (setq tem (file-symlink-p newname))
540 541 542 543 544 545 546 547 548 549 550 551 552 553 554 555 556 557 558 559 560
      (save-match-data
	(if (= count 0)
	    (error "Apparent cycle of symbolic links for %s" filename))
	;; In the context of a link, `//' doesn't mean what Emacs thinks.
	(while (string-match "//+" tem)
	  (setq tem (replace-match "/" nil nil tem)))
	;; Handle `..' by hand, since it needs to work in the
	;; target of any directory symlink.
	;; This code is not quite complete; it does not handle
	;; embedded .. in some cases such as ./../foo and foo/bar/../../../lose.
	(while (string-match "\\`\\.\\./" tem)
	  (setq tem (substring tem 3))
	  (setq newname (expand-file-name newname))
	  ;; Chase links in the default dir of the symlink.
	  (setq newname
		(file-chase-links
		 (directory-file-name (file-name-directory newname))))
	  ;; Now find the parent of that dir.
	  (setq newname (file-name-directory newname)))
	(setq newname (expand-file-name tem (file-name-directory newname)))
	(setq count (1- count))))
561
    newname))
Roland McGrath's avatar
Roland McGrath committed
562

563 564 565 566
(defun switch-to-buffer-other-window (buffer &optional norecord)
  "Select buffer BUFFER in another window.
Optional second arg NORECORD non-nil means
do not put this buffer at the front of the list of recently selected ones."
Roland McGrath's avatar
Roland McGrath committed
567 568
  (interactive "BSwitch to buffer in other window: ")
  (let ((pop-up-windows t))
569
    (pop-to-buffer buffer t norecord)))
Roland McGrath's avatar
Roland McGrath committed
570

571 572 573 574
(defun switch-to-buffer-other-frame (buffer &optional norecord)
  "Switch to buffer BUFFER in another frame.
Optional second arg NORECORD non-nil means
do not put this buffer at the front of the list of recently selected ones."
Jim Blandy's avatar
Jim Blandy committed
575 576
  (interactive "BSwitch to buffer in other frame: ")
  (let ((pop-up-frames t))
577
    (pop-to-buffer buffer t norecord)
578
    (raise-frame (window-frame (selected-window)))))
Jim Blandy's avatar
Jim Blandy committed
579

580
(defun find-file (filename)
Roland McGrath's avatar
Roland McGrath committed
581 582
  "Edit file FILENAME.
Switch to a buffer visiting file FILENAME,
583 584 585
creating one if none already exists."
  (interactive "FFind file: ")
  (switch-to-buffer (find-file-noselect filename)))
586

587
(defun find-file-other-window (filename)
Roland McGrath's avatar
Roland McGrath committed
588 589 590
  "Edit file FILENAME, in another window.
May create a new window, or reuse an existing one.
See the function `display-buffer'."
591 592
  (interactive "FFind file in other window: ")
  (switch-to-buffer-other-window (find-file-noselect filename)))
Roland McGrath's avatar
Roland McGrath committed
593

594
(defun find-file-other-frame (filename)
Jim Blandy's avatar
Jim Blandy committed
595 596
  "Edit file FILENAME, in another frame.
May create a new frame, or reuse an existing one.
Jim Blandy's avatar
Jim Blandy committed
597
See the function `display-buffer'."
598 599
  (interactive "FFind file in other frame: ")
  (switch-to-buffer-other-frame (find-file-noselect filename)))
Jim Blandy's avatar
Jim Blandy committed
600

601
(defun find-file-read-only (filename)
Roland McGrath's avatar
Roland McGrath committed
602 603 604
  "Edit file FILENAME but don't allow changes.
Like \\[find-file] but marks buffer as read-only.
Use \\[toggle-read-only] to permit editing."
605 606
  (interactive "fFind file read-only: ")
  (find-file filename)
607
  (toggle-read-only 1)
608
  (current-buffer))
Roland McGrath's avatar
Roland McGrath committed
609

610
(defun find-file-read-only-other-window (filename)
Roland McGrath's avatar
Roland McGrath committed
611 612 613
  "Edit file FILENAME in another window but don't allow changes.
Like \\[find-file-other-window] but marks buffer as read-only.
Use \\[toggle-read-only] to permit editing."
614 615
  (interactive "fFind file read-only other window: ")
  (find-file-other-window filename)
616
  (toggle-read-only 1)
617
  (current-buffer))
Roland McGrath's avatar
Roland McGrath committed
618

619
(defun find-file-read-only-other-frame (filename)
Jim Blandy's avatar
Jim Blandy committed
620 621
  "Edit file FILENAME in another frame but don't allow changes.
Like \\[find-file-other-frame] but marks buffer as read-only.
Jim Blandy's avatar
Jim Blandy committed
622
Use \\[toggle-read-only] to permit editing."
623 624
  (interactive "fFind file read-only other frame: ")
  (find-file-other-frame filename)
625
  (toggle-read-only 1)
626
  (current-buffer))
Jim Blandy's avatar
Jim Blandy committed
627

628
(defun find-alternate-file-other-window (filename)
629
  "Find file FILENAME as a replacement for the file in the next window.
630
This command does not select that window."
631 632 633 634 635 636 637 638 639 640
  (interactive
   (save-selected-window
     (other-window 1)
     (let ((file buffer-file-name)
	   (file-name nil)
	   (file-dir nil))
       (and file
	    (setq file-name (file-name-nondirectory file)
		  file-dir (file-name-directory file)))
       (list (read-file-name
641
	      "Find alternate file: " file-dir nil nil file-name)))))
642
  (if (one-window-p)
643
      (find-file-other-window filename)
644 645
    (save-selected-window
      (other-window 1)
646
      (find-alternate-file filename))))
647

648
(defun find-alternate-file (filename)
Roland McGrath's avatar
Roland McGrath committed
649 650
  "Find file FILENAME, select its buffer, kill previous buffer.
If the current buffer now contains an empty file that you just visited
651
\(presumably by mistake), use this command to visit the file you really want."
Roland McGrath's avatar
Roland McGrath committed
652 653 654 655 656 657 658
  (interactive
   (let ((file buffer-file-name)
	 (file-name nil)
	 (file-dir nil))
     (and file
	  (setq file-name (file-name-nondirectory file)
		file-dir (file-name-directory file)))
Joseph Arceneaux's avatar
Joseph Arceneaux committed
659
     (list (read-file-name
660
	    "Find alternate file: " file-dir nil nil file-name))))
661
  (and (buffer-modified-p) (buffer-file-name)
Roland McGrath's avatar
Roland McGrath committed
662 663 664 665 666 667
       ;; (not buffer-read-only)
       (not (yes-or-no-p (format "Buffer %s is modified; kill anyway? "
				 (buffer-name))))
       (error "Aborted"))
  (let ((obuf (current-buffer))
	(ofile buffer-file-name)
668 669
	(onum buffer-file-number)
	(otrue buffer-file-truename)
Roland McGrath's avatar
Roland McGrath committed
670
	(oname (buffer-name)))
671 672
    (if (get-buffer " **lose**")
	(kill-buffer " **lose**"))
Roland McGrath's avatar
Roland McGrath committed
673 674 675 676
    (rename-buffer " **lose**")
    (unwind-protect
	(progn
	  (unlock-buffer)
677 678 679
	  (setq buffer-file-name nil)
	  (setq buffer-file-number nil)
	  (setq buffer-file-truename nil)
680
	  (find-file filename))
Roland McGrath's avatar
Roland McGrath committed
681 682
      (cond ((eq obuf (current-buffer))
	     (setq buffer-file-name ofile)
683 684
	     (setq buffer-file-number onum)
	     (setq buffer-file-truename otrue)
Roland McGrath's avatar
Roland McGrath committed
685 686 687 688 689 690 691 692 693 694 695 696 697 698
	     (lock-buffer)
	     (rename-buffer oname))))
    (or (eq (current-buffer) obuf)
	(kill-buffer obuf))))

(defun create-file-buffer (filename)
  "Create a suitably named buffer for visiting FILENAME, and return it.
FILENAME (sans directory) is used unchanged if that name is free;
otherwise a string <2> or <3> or ... is appended to get an unused name."
  (let ((lastname (file-name-nondirectory filename)))
    (if (string= lastname "")
	(setq lastname filename))
    (generate-new-buffer lastname)))

Jim Blandy's avatar
Jim Blandy committed
699 700
(defun generate-new-buffer (name)
  "Create and return a buffer with a name based on NAME.
Richard M. Stallman's avatar
Richard M. Stallman committed
701
Choose the buffer's name using `generate-new-buffer-name'."
Jim Blandy's avatar
Jim Blandy committed
702 703
  (get-buffer-create (generate-new-buffer-name name)))

704
(defvar automount-dir-prefix "^/tmp_mnt/"
Jim Blandy's avatar
Jim Blandy committed
705 706
  "Regexp to match the automounter prefix in a directory name.")

707
(defvar abbreviated-home-dir nil
708
  "The user's homedir abbreviated according to `directory-abbrev-list'.")
709

Jim Blandy's avatar
Jim Blandy committed
710
(defun abbreviate-file-name (filename)
Richard M. Stallman's avatar
Richard M. Stallman committed
711
  "Return a version of FILENAME shortened using `directory-abbrev-alist'.
Jim Blandy's avatar
Jim Blandy committed
712
This also substitutes \"~\" for the user's home directory.
Richard M. Stallman's avatar
Richard M. Stallman committed
713
Type \\[describe-variable] directory-abbrev-alist RET for more information."
Jim Blandy's avatar
Jim Blandy committed
714
  ;; Get rid of the prefixes added by the automounter.
715 716
  (if (and automount-dir-prefix
	   (string-match automount-dir-prefix filename)
Jim Blandy's avatar
Jim Blandy committed
717 718 719
	   (file-exists-p (file-name-directory
			   (substring filename (1- (match-end 0))))))
      (setq filename (substring filename (1- (match-end 0)))))
Jim Blandy's avatar
Jim Blandy committed
720
  (let ((tail directory-abbrev-alist))
721 722
    ;; If any elt of directory-abbrev-alist matches this name,
    ;; abbreviate accordingly.
Jim Blandy's avatar
Jim Blandy committed
723 724 725 726 727
    (while tail
      (if (string-match (car (car tail)) filename)
	  (setq filename
		(concat (cdr (car tail)) (substring filename (match-end 0)))))
      (setq tail (cdr tail)))
728 729 730
    ;; Compute and save the abbreviated homedir name.
    ;; We defer computing this until the first time it's needed, to
    ;; give time for directory-abbrev-alist to be set properly.
731 732
    ;; We include a slash at the end, to avoid spurious matches
    ;; such as `/usr/foobar' when the home dir is `/usr/foo'.
733 734 735
    (or abbreviated-home-dir
	(setq abbreviated-home-dir
	      (let ((abbreviated-home-dir "$foo"))
736 737
		(concat "^" (abbreviate-file-name (expand-file-name "~"))
			"\\(/\\|$\\)"))))
738

739 740
    ;; If FILENAME starts with the abbreviated homedir,
    ;; make it start with `~' instead.
741 742 743
    (if (and (string-match abbreviated-home-dir filename)
	     ;; If the home dir is just /, don't change it.
	     (not (and (= (match-end 0) 1)
744
		       (= (aref filename 0) ?/)))
745 746
	     ;; MS-DOS root directories can come with a drive letter;
	     ;; Novell Netware allows drive letters beyond `Z:'.
747
	     (not (and (or (eq system-type 'ms-dos)
748
			   (eq system-type 'windows-nt))
749
		       (save-match-data
750
			 (string-match "^[a-zA-`]:/$" filename)))))
Jim Blandy's avatar
Jim Blandy committed
751
	(setq filename
752
	      (concat "~"
753
		      (substring filename (match-beginning 1) (match-end 1))
754
		      (substring filename (match-end 0)))))
Jim Blandy's avatar
Jim Blandy committed
755 756
    filename))

757
(defcustom find-file-not-true-dirname-list nil
758 759 760 761
  "*List of logical names for which visiting shouldn't save the true dirname.
On VMS, when you visit a file using a logical name that searches a path,
you may or may not want the visited file name to record the specific
directory where the file was found.  If you *do not* want that, add the logical
762 763 764
name to this list as a string."
  :type '(repeat (string :tag "Name"))
  :group 'find-file)
765

766 767 768 769 770 771 772 773 774 775 776 777 778 779 780 781 782
(defun find-buffer-visiting (filename)
  "Return the buffer visiting file FILENAME (a string).
This is like `get-file-buffer', except that it checks for any buffer
visiting the same file, possibly under a different name.
If there is no such live buffer, return nil."
  (let ((buf (get-file-buffer filename))
	(truename (abbreviate-file-name (file-truename filename))))
    (or buf
	(let ((list (buffer-list)) found)
	  (while (and (not found) list)
	    (save-excursion
	      (set-buffer (car list))
	      (if (and buffer-file-name
		       (string= buffer-file-truename truename))
		  (setq found (car list))))
	    (setq list (cdr list)))
	  found)
783
	(let ((number (nthcdr 10 (file-attributes truename)))
784
	      (list (buffer-list)) found)
785 786
	  (and buffer-file-numbers-unique
	       number
787 788 789
	       (while (and (not found) list)
		 (save-excursion
		   (set-buffer (car list))
790 791
		   (if (and buffer-file-name
			    (equal buffer-file-number number)
792 793 794 795 796 797 798
			    ;; Verify this buffer's file number
			    ;; still belongs to its file.
			    (file-exists-p buffer-file-name)
			    (equal (nthcdr 10 (file-attributes buffer-file-name))
				   number))
		       (setq found (car list))))
		 (setq list (cdr list))))
799 800
	  found))))

801 802 803 804 805
(defun insert-file-contents-literally (filename &optional visit beg end replace)
  "Like `insert-file-contents', q.v., but only reads in the file.
A buffer may be modified in several ways after reading into the buffer due
to advanced Emacs features, such as file-name-handlers, format decoding,
find-file-hooks, etc.
806 807 808 809
  This function ensures that none of these modifications will take place.

This function does not work for remote files, because it turns off
file name handlers and remote file access uses a file name handler."
810 811 812
  (let ((file-name-handler-alist nil)
	(format-alist nil)
	(after-insert-file-functions nil)
813
	(find-buffer-file-type-function
814 815 816 817 818 819 820 821 822 823 824 825
	 (if (fboundp 'find-buffer-file-type)
	     (symbol-function 'find-buffer-file-type)
	   nil)))
    (unwind-protect
	(progn
	  (fset 'find-buffer-file-type (lambda (filename) t))
	  (insert-file-contents filename visit beg end replace))
      (if find-buffer-file-type-function
	  (fset 'find-buffer-file-type find-buffer-file-type-function)
	(fmakunbound 'find-buffer-file-type)))))

(defun find-file-noselect (filename &optional nowarn rawfile)
Roland McGrath's avatar
Roland McGrath committed
826 827 828
  "Read file FILENAME into a buffer and return the buffer.
If a buffer exists visiting FILENAME, return that one, but
verify that the file has not changed since visited or saved.
829 830 831
The buffer is not selected, just returned to the caller.
Optional first arg NOWARN non-nil means suppress any warning messages.
Optional second arg RAWFILE non-nil means the file is read literally"
Jim Blandy's avatar
Jim Blandy committed
832 833 834
  (setq filename
	(abbreviate-file-name
	 (expand-file-name filename)))
Roland McGrath's avatar
Roland McGrath committed
835 836
  (if (file-directory-p filename)
      (if find-file-run-dired
837 838 839
	  (dired-noselect (if find-file-visit-truename
			      (abbreviate-file-name (file-truename filename))
			    filename))
840
	(error "%s is a directory" filename))
841 842 843 844
    (let* ((buf (get-file-buffer filename))
	   (truename (abbreviate-file-name (file-truename filename)))
	   (number (nthcdr 10 (file-attributes truename)))
	   ;; Find any buffer for a file which has same truename.
845
	   (other (and (not buf) (find-buffer-visiting filename)))
846 847
	   error)
      ;; Let user know if there is a buffer with the same truename.
848 849
      (if other
	  (progn
850 851 852 853
	    (or nowarn
		(string-equal filename (buffer-file-name other))
		(message "%s and %s are the same file"
			 filename (buffer-file-name other)))
854 855 856
	    ;; Optionally also find that buffer.
	    (if (or find-file-existing-other-name find-file-visit-truename)
		(setq buf other))))
Roland McGrath's avatar
Roland McGrath committed
857 858 859 860 861
      (if buf
	  (or nowarn
	      (verify-visited-file-modtime buf)
	      (cond ((not (file-exists-p filename))
		     (error "File %s no longer exists!" filename))
862 863 864
		    ;; Certain files should be reverted automatically
		    ;; if they have changed on disk and not in the buffer.
		    ((and (not (buffer-modified-p buf))
865
			  (let ((tail revert-without-query)
866 867 868 869 870 871 872 873 874 875
				(found nil))
			    (while tail
			      (if (string-match (car tail) filename)
				  (setq found t))
			      (setq tail (cdr tail)))
			    found))
		     (with-current-buffer buf
		      (message "Reverting file %s..." filename)
		      (revert-buffer t t)
		      (message "Reverting file %s...done" filename)))
Roland McGrath's avatar
Roland McGrath committed
876
		    ((yes-or-no-p
877 878 879 880 881 882 883 884 885 886 887 888 889
		      (if (string= (file-name-nondirectory filename)
				   (buffer-name buf))
			  (format
			   (if (buffer-modified-p buf)
	"File %s changed on disk.  Discard your edits? "
	"File %s changed on disk.  Reread from disk? ")
			   (file-name-nondirectory filename))
			(format
			 (if (buffer-modified-p buf)
      "File %s changed on disk.  Discard your edits in %s? "
      "File %s changed on disk.  Reread from disk into %s? ")
			 (file-name-nondirectory filename)
			 (buffer-name buf))))
890
		     (with-current-buffer buf
Roland McGrath's avatar
Roland McGrath committed
891 892
		       (revert-buffer t t)))))
	(save-excursion
893 894 895 896 897 898 899
;;; The truename stuff makes this obsolete.
;;;	  (let* ((link-name (car (file-attributes filename)))
;;;		 (linked-buf (and (stringp link-name)
;;;				  (get-file-buffer link-name))))
;;;	    (if (bufferp linked-buf)
;;;		(message "Symbolic link to file in buffer %s"
;;;			 (buffer-name linked-buf))))
Roland McGrath's avatar
Roland McGrath committed
900
	  (setq buf (create-file-buffer filename))
901
	  (set-buffer-major-mode buf)
Roland McGrath's avatar
Roland McGrath committed
902 903
	  (set-buffer buf)
	  (erase-buffer)
904 905 906 907 908 909 910 911 912 913 914 915 916
	  (if rawfile
	      (condition-case ()
		  (insert-file-contents-literally filename t)
		(file-error
		 ;; Unconditionally set error
		 (setq error t)))
	    (condition-case ()
		(insert-file-contents filename t)
	      (file-error
	       ;; Run find-file-not-found-hooks until one returns non-nil.
	       (or (run-hook-with-args-until-success 'find-file-not-found-hooks)
		   ;; If they fail too, set error.
		   (setq error t)))))
917
	  ;; Find the file's truename, and maybe use that as visited name.
918
	  (setq buffer-file-truename truename)
919 920 921 922 923 924 925 926 927 928
	  (setq buffer-file-number number)
	  ;; On VMS, we may want to remember which directory in a search list
	  ;; the file was found in.
	  (and (eq system-type 'vax-vms)
	       (let (logical)
		 (if (string-match ":" (file-name-directory filename))
		     (setq logical (substring (file-name-directory filename)
					      0 (match-beginning 0))))
		 (not (member logical find-file-not-true-dirname-list)))
	       (setq buffer-file-name buffer-file-truename))
929
	  (if find-file-visit-truename
930 931 932
	      (setq buffer-file-name
		    (setq filename
			  (expand-file-name buffer-file-truename))))
Roland McGrath's avatar
Roland McGrath committed
933 934 935 936 937 938 939 940
	  ;; Set buffer's default directory to that of the file.
	  (setq default-directory (file-name-directory filename))
	  ;; Turn off backup files for certain file names.  Since
	  ;; this is a permanent local, the major mode won't eliminate it.
	  (and (not (funcall backup-enable-predicate buffer-file-name))
	       (progn
		 (make-local-variable 'backup-inhibited)
		 (setq backup-inhibited t)))
941 942
	  (if rawfile
	      nil
943 944
	    (after-find-file error (not nowarn))
	    (setq buf (current-buffer)))))
Roland McGrath's avatar
Roland McGrath committed
945 946
      buf)))

947 948
(defvar after-find-file-from-revert-buffer nil)

949
(defun after-find-file (&optional error warn noauto
950 951
				  after-find-file-from-revert-buffer
				  nomodes)
Roland McGrath's avatar
Roland McGrath committed
952 953
  "Called after finding a file and by the default revert function.
Sets buffer mode, parses local variables.
954
Optional args ERROR, WARN, and NOAUTO: ERROR non-nil means there was an
Roland McGrath's avatar
Roland McGrath committed
955 956
error in reading the file.  WARN non-nil means warn if there
exists an auto-save file more recent than the visited file.
957
NOAUTO means don't mess with auto-save mode.
958 959
Fourth arg AFTER-FIND-FILE-FROM-REVERT-BUFFER non-nil
 means this call was from `revert-buffer'.
960 961 962
Fifth arg NOMODES non-nil means don't alter the file's modes.
Finishes by calling the functions in `find-file-hooks'
unless NOMODES is non-nil."
Roland McGrath's avatar
Roland McGrath committed
963 964 965 966 967 968 969
  (setq buffer-read-only (not (file-writable-p buffer-file-name)))
  (if noninteractive
      nil
    (let* (not-serious
	   (msg
	    (cond ((and error (file-attributes buffer-file-name))
		   (setq buffer-read-only t)
970
		   "File exists, but cannot be read.")
Roland McGrath's avatar
Roland McGrath committed
971 972 973 974
		  ((not buffer-read-only)
		   (if (and warn
			    (file-newer-than-file-p (make-auto-save-file-name)
						    buffer-file-name))
975 976
		       (format "%s has auto save data; consider M-x recover-file"
			       (file-name-nondirectory buffer-file-name))
Roland McGrath's avatar
Roland McGrath committed
977 978 979 980 981 982 983
		     (setq not-serious t)
		     (if error "(New file)" nil)))
		  ((not error)
		   (setq not-serious t)
		   "Note: file is write protected")
		  ((file-attributes (directory-file-name default-directory))
		   "File not found and directory write-protected")
984 985
		  ((file-exists-p (file-name-directory buffer-file-name))
		   (setq buffer-read-only nil))
Roland McGrath's avatar
Roland McGrath committed
986
		  (t
Jim Blandy's avatar
Jim Blandy committed
987
		   (setq buffer-read-only nil)
988 989 990
		   (if (file-exists-p (file-name-directory (directory-file-name (file-name-directory buffer-file-name))))
		       "Use M-x make-dir RET RET to create the directory"
		     "Use C-u M-x make-dir RET RET to create directory and its parents")))))
Roland McGrath's avatar
Roland McGrath committed
991 992 993 994
      (if msg
	  (progn
	    (message msg)
	    (or not-serious (sit-for 1 nil t)))))
995
    (if (and auto-save-default (not noauto))
Roland McGrath's avatar
Roland McGrath committed
996
	(auto-save-mode t)))
997