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files.el
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;;; files.el --- file input and output commands -*- lexical-binding:t -*-
;; Copyright (C) 1985-1987, 1992-2025 Free Software Foundation, Inc.
;; Maintainer: emacs-devel@gnu.org
;; Package: emacs
;; 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
;; the Free Software Foundation, either version 3 of the License, or
;; (at your option) any later version.
;; GNU Emacs is distributed in the hope that it will be useful,
;; but WITHOUT ANY WARRANTY; without even the implied warranty of
;; MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
;; GNU General Public License for more details.
;; You should have received a copy of the GNU General Public License
;; along with GNU Emacs. If not, see <https://www.gnu.org/licenses/>.
;;; Commentary:
;; Defines Emacs's basic file- and directory-handling functions,
;; including file visiting, backup file generation and versioning,
;; link handling, load- and write-hook handling, and the like.
;;; Code:
(eval-when-compile
(require 'pcase)
(require 'easy-mmode)) ; For `define-minor-mode'.
(defvar font-lock-keywords)
(defgroup backup nil
"Backups of edited data files."
:group 'files)
(defgroup find-file nil
"Finding files."
:group 'files)
(defcustom directory-abbrev-alist
nil
"Alist of abbreviations for file directories.
A list of elements of the form (FROM . TO), each meaning to replace
a match for FROM with TO when a directory name matches FROM. This
replacement is done when setting up the default directory of a
newly visited file buffer.
FROM is a regexp that 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 \"^\".
FROM and TO should be equivalent names, which refer to the
same directory. TO should be an absolute directory name.
Do not use `~' in the TO strings.
Use this feature when you have directories that you normally refer to
via absolute symbolic links. Make TO the name of the link, and FROM
a regexp matching the name it is linked to."
:type '(repeat (cons :format "%v"
:value ("\\`" . "")
(regexp :tag "From")
(string :tag "To")))
:group 'abbrev
:group 'find-file)
(defun directory-abbrev-make-regexp (directory)
"Create a regexp to match DIRECTORY for `directory-abbrev-alist'."
(let ((regexp
;; We include a slash at the end, to avoid spurious
;; matches such as `/usr/foobar' when the home dir is
;; `/usr/foo'.
(concat "\\`" (regexp-quote directory) "\\(/\\|\\'\\)")))
;; The value of regexp could be multibyte or unibyte. In the
;; latter case, we need to decode it.
(if (multibyte-string-p regexp)
regexp
(decode-coding-string regexp
(if (eq system-type 'windows-nt)
'utf-8
locale-coding-system)))))
(defun directory-abbrev-apply (filename)
"Apply the abbreviations in `directory-abbrev-alist' to FILENAME.
Note that when calling this, you should set `case-fold-search' as
appropriate for the filesystem used for FILENAME."
(dolist (dir-abbrev directory-abbrev-alist filename)
(when (string-match (car dir-abbrev) filename)
(setq filename (concat (cdr dir-abbrev)
(substring filename (match-end 0)))))))
(defcustom make-backup-files t
"Non-nil means make a backup of a file the first time it is saved.
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',
`backup-by-copying-when-mismatch' and
`backup-by-copying-when-privileged-mismatch'. See also `backup-inhibited'."
:type 'boolean
:group 'backup)
;; Do this so that local variables based on the file name
;; are not overridden by the major mode.
(defvar backup-inhibited nil
"If non-nil, backups will be inhibited.
This variable is intended for use by making it local to a buffer,
but it is not an automatically buffer-local variable.")
(put 'backup-inhibited 'permanent-local t)
(defcustom backup-by-copying nil
"Non-nil means always use copying to create backup files.
See documentation of variable `make-backup-files'."
:type 'boolean
:group 'backup)
(defcustom backup-by-copying-when-linked nil
"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.
This variable is relevant only if `backup-by-copying' is nil."
:type 'boolean
:group 'backup)
(defcustom backup-by-copying-when-mismatch t
"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 that are owned by you and whose group matches
the default for a new file created there by you.
This variable is relevant only if `backup-by-copying' is nil."
:version "24.1"
:type 'boolean
:local 'permanent-only
:group 'backup)
(defcustom backup-by-copying-when-privileged-mismatch 200
"Non-nil means create backups by copying to preserve a privileged owner.
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
user id and group id of the file are both greater than the value of
this variable. This is useful when low-numbered uid's and gid'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
"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.")
(defcustom buffer-offer-save nil
"Non-nil in a buffer means always offer to save buffer on exiting Emacs.
Do so even if the buffer is not visiting a file.
Automatically local in all buffers.
Set to the symbol `always' to offer to save buffer whenever
`save-some-buffers' is called.
Note that this option has no effect on `kill-buffer';
if you want to control what happens when a buffer is killed,
use `kill-buffer-query-functions'."
:type '(choice (const :tag "Never" nil)
(const :tag "On Emacs exit" t)
(const :tag "Whenever save-some-buffers is called" always))
:local 'permanent
:group 'backup)
(defcustom find-file-existing-other-name t
"Non-nil means find a file under alternative names, in existing buffers.
This means if any existing buffer is visiting the file you want
under another name, you get the existing buffer instead of a new buffer."
:type 'boolean
:group 'find-file)
(defcustom find-file-visit-truename nil
"Non-nil means visiting a file uses its truename as the visited-file name.
That is, the buffer visiting the file has the truename as the
value of `buffer-file-name'. The truename of a file is found by
chasing all links both at the file level and at the levels of the
containing directories."
:type 'boolean
:group 'find-file)
(defcustom revert-without-query nil
"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,
then `revert-buffer' reverts the file without querying
if the file has changed on disk and you have not edited the buffer."
:type '(repeat regexp)
:group 'find-file)
(defvar-local buffer-file-number nil
"The inode number and the device of the file visited in the current buffer.
The value is a list of the form (INODENUM DEVICE), where DEVICE can be
either a single number or a cons cell of two numbers.
This tuple of numbers uniquely identifies the file.
If the buffer is visiting a new file, the value is nil.")
(put 'buffer-file-number 'permanent-local t)
(defvar buffer-file-numbers-unique (not (memq system-type '(windows-nt)))
"Non-nil means that `buffer-file-number' uniquely identifies files.")
(defvar-local buffer-file-read-only nil
"Non-nil if visited file was read-only when visited.")
(defcustom small-temporary-file-directory
(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
have fast storage with limited space, such as a RAM disk."
:group 'files
:initialize #'custom-initialize-delay
:type '(choice (const nil) directory))
;; The system null device. (Should reference NULL_DEVICE from C.)
(defvar null-device "/dev/null" "The system null device.")
(declare-function msdos-long-file-names "msdos.c")
(declare-function w32-long-file-name "w32proc.c")
(declare-function dired-get-filename "dired" (&optional localp no-error-if-not-filep))
(declare-function dired-unmark "dired" (arg &optional interactive))
(declare-function dired-do-flagged-delete "dired" (&optional nomessage))
(declare-function dos-8+3-filename "dos-fns" (filename))
(declare-function dosified-file-name "dos-fns" (file-name))
(defvar file-name-invalid-regexp
(cond ((and (eq system-type 'ms-dos) (not (msdos-long-file-names)))
(concat "^\\([^A-Z[-`a-z]\\|..+\\)?:\\|" ; colon except after drive
"[+, ;=|<>\"?*]\\|\\[\\|\\]\\|" ; invalid characters
"[\000-\037]\\|" ; control characters
"\\(/\\.\\.?[^/]\\)\\|" ; leading dots
"\\(/[^/.]+\\.[^/.]*\\.\\)")) ; more than a single dot
((memq system-type '(ms-dos windows-nt cygwin))
(concat "^\\([^A-Z[-`a-z]\\|..+\\)?:\\|" ; colon except after drive
"[|<>\"?*\000-\037]")) ; invalid characters
(t "[\000]"))
"Regexp recognizing file names that aren't allowed by the filesystem.")
(defcustom file-precious-flag nil
"Non-nil means protect against I/O errors while saving files.
Some modes set this non-nil in particular buffers.
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.
Yet, at the same time, saving a precious file
breaks any hard links between it and other files.
This feature is advisory: for example, if the directory in which the
file is being saved is not writable, Emacs may ignore a non-nil value
of `file-precious-flag' and write directly into the file.
See also: `break-hardlink-on-save' and `file-preserve-symlinks-on-save'."
:type 'boolean
:group 'backup)
(defcustom break-hardlink-on-save nil
"Whether to allow breaking hardlinks when saving files.
If non-nil, then when saving a file that exists under several
names \(i.e., has multiple hardlinks), break the hardlink
associated with `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
itself writable, then error instead of saving in some
hardlink-nonbreaking way.
See also `backup-by-copying' and `backup-by-copying-when-linked'."
:type 'boolean
:group 'files
:version "23.1")
(defcustom version-control nil
"Control use of version-numbered backup files.
When t, make numbered backup files unconditionally.
When nil, make them for files that already have numbered backups.
The value `never' means never make numbered backups."
:type '(choice (const :tag "Never" never)
(const :tag "If numbered backups exist" nil)
(other :tag "Always" t))
:safe #'version-control-safe-local-p
:group 'backup)
(defun version-control-safe-local-p (x)
"Return whether X is safe as local value for `version-control'."
(or (booleanp x) (equal x 'never)))
(defcustom dired-kept-versions 2
"When cleaning directory, number of versions of numbered backups to keep.
See `version-control', `kept-old-versions' and `kept-new-versions' for
more about keeping and deleting old versioned (a.k.a. \"numbered\")
backup files."
:type 'natnum
:group 'backup
:group 'dired)
(defcustom delete-old-versions nil
"If t, delete excess numbered backup files silently.
If nil, ask confirmation. Any other value prevents any trimming.
See `version-control', `kept-old-versions', `kept-new-versions'
and `dired-kept-versions' for more about keeping and deleting old
versioned (a.k.a. \"numbered\") backup files."
:type '(choice (const :tag "Delete" t)
(const :tag "Ask" nil)
(other :tag "Leave" other))
:group 'backup)
(defcustom kept-old-versions 2
"Number of oldest versions to keep when a new numbered backup is made.
See `version-control' for how Emacs decides when to make numbered backups."
:type 'natnum
:safe #'natnump
:group 'backup)
(defcustom kept-new-versions 2
"Number of newest versions to keep when a new numbered backup is made.
Includes the new backup. Must be greater than 0.
See `version-control' for how Emacs decides when to make numbered backups."
:type 'natnum
:safe #'natnump
:group 'backup)
(defcustom require-final-newline nil
"Whether to add a newline automatically at the end of the file.
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.
A value of nil means don't add newlines.
Certain major modes set this locally to the value obtained
from `mode-require-final-newline'.
This variable is heeded only when visiting files (or saving
buffers into files they visit). Writing data to the file system
with `write-region' and the like is not influenced by this variable."
:safe #'symbolp
:type '(choice (const :tag "When visiting" visit)
(const :tag "When saving" t)
(const :tag "When visiting or saving" visit-save)
(const :tag "Don't add newlines" nil)
(other :tag "Ask each time" ask))
:group 'editing-basics)
(defcustom mode-require-final-newline t
"Whether to add a newline at end of file, in certain major modes.
Those modes set `require-final-newline' to this value when you enable them.
They do so because they are often used for files that are supposed
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.
Any other non-nil value means ask user whether to add a newline, when saving.
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."
:type '(choice (const :tag "When visiting" visit)
(const :tag "When saving" t)
(const :tag "When visiting or saving" visit-save)
(const :tag "Don't add newlines" nil)
(other :tag "Ask each time" ask))
:group 'editing-basics
:version "22.1")
(defcustom auto-save-default t
"Non-nil says by default do auto-saving of every file-visiting buffer."
:type 'boolean
:group 'auto-save)
(defcustom auto-save-file-name-transforms
`(("\\`/[^/]*:\\([^/]*/\\)*\\([^/]*\\)\\'"
;; Don't put "\\2" inside expand-file-name, since it will be
;; transformed to "/2" on DOS/Windows.
,(concat temporary-file-directory "\\2") t))
"Transforms to apply to buffer file name before making auto-save file name.
Each transform is a list (REGEXP REPLACEMENT UNIQUIFY):
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.
If the optional element UNIQUIFY is nil, Emacs does not check for
file name clashes, so using that is not recommended. If UNIQUIFY
is one of the members of `secure-hash-algorithms', Emacs
constructs the nondirectory part of the auto-save file name by
applying that `secure-hash' to the buffer file name. This avoids
any risk of excessively long file names. Finally, if UNIQUIFY is
any other value the auto-save file name is constructed by taking
the directory part of the replaced file-name, 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.
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.
The default value is set up to put the auto-save file into the
temporary directory (see the variable `temporary-file-directory') for
editing a remote file.
On MS-DOS filesystems without long names this variable is always
ignored."
:group 'auto-save
:type `(repeat (list (regexp :tag "Regexp")
(string :tag "Replacement")
(choice
(const :tag "Uniquify" t)
,@(mapcar (lambda (algo)
(list 'const algo))
(secure-hash-algorithms)))))
:initialize #'custom-initialize-delay
:version "21.1")
(defvar auto-save--timer nil "Timer for `auto-save-visited-mode'.")
(defcustom auto-save-visited-interval 5
"Interval in seconds for `auto-save-visited-mode'.
If `auto-save-visited-mode' is enabled, Emacs will save all
buffers visiting a file to the visited file after it has been
idle for `auto-save-visited-interval' seconds."
:group 'auto-save
:type 'number
:version "26.1"
:set (lambda (symbol value)
(set-default symbol value)
(when auto-save--timer
(timer-set-idle-time auto-save--timer value :repeat))))
(defcustom auto-save-visited-predicate nil
"Predicate function for `auto-save-visited-mode'.
If non-nil, the value should be a function of no arguments; it
will be called once in each file-visiting buffer when the time
comes to auto-save. A buffer will be saved only if the predicate
function returns a non-nil value.
For example, you could add this to your Init file to only save
files that are both in Org mode and in a particular directory:
(setq auto-save-visited-predicate
(lambda () (and (eq major-mode \\='org-mode)
(string-match \"^/home/skangas/org/\"
buffer-file-name))))
If the value of this variable is not a function, it is ignored.
This is the same as having a predicate that always returns
non-nil."
:group 'auto-save
:type '(choice :tag "Function:"
(const :tag "No extra predicate" :value nil)
(function :tag "Predicate function" :value always))
:risky t
:version "29.1")
(defcustom remote-file-name-inhibit-auto-save-visited nil
"When nil, `auto-save-visited-mode' will auto-save remote files.
Any other value means that it will not."
:group 'auto-save
:group 'tramp
:type 'boolean
:version "29.1")
(define-minor-mode auto-save-visited-mode
"Toggle automatic saving of file-visiting buffers to their files.
When this mode is enabled, file-visiting buffers are automatically
saved to their files. This is in contrast to `auto-save-mode', which
auto-saves those buffers to a separate file, leaving the original
file intact. See Info node `Saving' for details of the save process.
The user option `auto-save-visited-interval' controls how often to
auto-save a buffer into its visited file.
You can use `auto-save-visited-predicate' to control which
buffers are saved.
You can also set the buffer-local value of the variable
`auto-save-visited-mode' to nil. A buffer where the buffer-local
value of this variable is nil is ignored for the purpose of
`auto-save-visited-mode', even if `auto-save-visited-mode' is
enabled.
For more details, see Info node `(emacs) Auto Save Files'."
:group 'auto-save
:global t
(when auto-save--timer (cancel-timer auto-save--timer))
(setq auto-save--timer
(when auto-save-visited-mode
(run-with-idle-timer
auto-save-visited-interval :repeat
#'save-some-buffers :no-prompt
(lambda ()
(and buffer-file-name
auto-save-visited-mode
(not (and buffer-auto-save-file-name
auto-save-visited-file-name))
(or (not (file-remote-p buffer-file-name))
(not remote-file-name-inhibit-auto-save-visited))
(or (not (functionp auto-save-visited-predicate))
(funcall auto-save-visited-predicate))))))))
;; The 'set' part is so we don't get a warning for using this variable
;; above, while still catching code that _sets_ the variable to get
;; the same effect as the new auto-save-visited-mode.
(make-obsolete-variable 'auto-save-visited-file-name 'auto-save-visited-mode
"Emacs 26.1" 'set)
(defcustom save-abbrevs t
"Non-nil means save word abbrevs too when files are saved.
If `silently', don't ask the user before saving."
:type '(choice (const t) (const nil) (const silently))
:group 'abbrev)
(defcustom lock-file-name-transforms nil
"Transforms to apply to buffer file name before making a lock file name.
This has the same syntax as `auto-save-file-name-transforms',
but applies to lock file names instead of auto-save file names.
By default, Emacs puts each lock file into the same directory as the
file it locks, prepending \".#\" to the base file name.
Note that changing this could break lock file functionality, e.g.:
if different users access the same file, using different lock file settings;
if accessing files on a shared file system from different hosts,
using a transform that puts the lock files on a local file system."
:group 'files
:type '(repeat (list (regexp :tag "Regexp")
(string :tag "Replacement")
(boolean :tag "Uniquify")))
:version "28.1")
(defcustom remote-file-name-inhibit-locks nil
"Whether to create file locks for remote files."
:group 'files
:group 'tramp
:version "28.1"
:type 'boolean)
(define-minor-mode lock-file-mode
"Toggle file locking in the current buffer (Lock File mode)."
:version "28.1"
(setq-local create-lockfiles (and lock-file-mode t)))
(defcustom find-file-run-dired t
"Non-nil means allow `find-file' to visit directories.
To visit the directory, `find-file' runs `find-directory-functions'."
:type 'boolean
:group 'find-file)
(defcustom find-directory-functions '(cvs-dired-noselect dired-noselect)
"List of functions to try in sequence to visit a directory.
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)
;; 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)
;;;It is not useful to make this a local variable.
;;;(put 'find-file-not-found-functions 'permanent-local t)
(defvar find-file-not-found-functions nil
"List of functions to be called for `find-file' on nonexistent file.
These functions are called as soon as the error is detected.
Variable `buffer-file-name' is already set up.
The functions are called in the order given until one of them returns non-nil.")
;;;It is not useful to make this a local variable.
;;;(put 'find-file-hook 'permanent-local t)
;; I found some external files still using the obsolete form in 2018.
(define-obsolete-variable-alias 'find-file-hooks 'find-file-hook "22.1")
(defcustom find-file-hook 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. This includes directory-local variables, if any,
for the file's directory."
:group 'find-file
:type 'hook
:options '(auto-insert)
:version "22.1")
;; I found some external files still using the obsolete form in 2018.
(define-obsolete-variable-alias 'write-file-hooks 'write-file-functions "22.1")
(defvar write-file-functions nil
"List of functions to be called before saving a buffer to a file.
Used only by `save-buffer'.
If one of them returns non-nil, the file is considered already written
and the rest are not called.
These hooks are considered to pertain to the visited file.
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.
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
updates before the buffer is saved, use `before-save-hook'.")
(put 'write-file-functions 'permanent-local t)
;; I found some files still using the obsolete form in 2018.
(defvar-local local-write-file-hooks nil)
(put 'local-write-file-hooks 'permanent-local t)
(make-obsolete-variable 'local-write-file-hooks 'write-file-functions "22.1")
;; I found some files still using the obsolete form in 2018.
(define-obsolete-variable-alias 'write-contents-hooks
'write-contents-functions "22.1")
(defvar-local write-contents-functions nil
"List of functions to be called before writing out a buffer to a file.
Used only by `save-buffer'. If one of them returns non-nil, the
file is considered already written and the rest are not called
and neither are the functions in `write-file-functions'. This
hook can thus be used to create save behavior for buffers that
are not visiting a file at all.
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
major mode does clear it.
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'.")
(defcustom enable-local-variables t
"Control use of local variables in files you visit.
The value can be t, nil, :safe, :all, or something else.
A value of t means file local variables specifications are obeyed
if all the specified variable values are safe; if any values are
not safe, Emacs queries you, once, whether to set them all.
\(When you say yes to certain values, they are remembered as safe.)
:safe means set the safe variables, and ignore the rest.
:all means set all variables, whether safe or not.
(Don't set it permanently to :all.)
A value of nil means always ignore the file local variables.
Any other value means always query you once whether to set them all.
\(When you say yes to certain values, they are remembered as safe, but
this has no effect when `enable-local-variables' is \"something else\".)
This variable also controls use of major modes specified in
a -*- line.
The command \\[normal-mode], when used interactively,
always obeys file local variable specifications and the -*- line,
and ignores this variable.
Also see the `permanently-enabled-local-variables' and
`safe-local-variable-directories' variables."
:risky t
:type '(choice (const :tag "Query Unsafe" t)
(const :tag "Safe Only" :safe)
(const :tag "Do all" :all)
(const :tag "Ignore" nil)
(other :tag "Query" other))
:group 'find-file)
(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.")
(defvar-local untrusted-content nil
"Non-nil means that current buffer originated from an untrusted source.
Email clients and some other modes may set this non-nil to mark the
buffer contents as untrusted.
This variable might be subject to change without notice.")
(put 'untrusted-content 'permanent-local t)
(defcustom trusted-content nil
"List of files and directories whose content we trust.
Be extra careful here since trusting means that Emacs might execute the
code contained within those files and directories without an explicit
request by the user.
One important case when this might happen is when `flymake-mode' is
enabled (for example, when it is added to a mode hook).
Each element of the list should be a string:
- If it ends in \"/\", it is considered as a directory name and means that
Emacs should trust all the files whose name has this directory as a prefix.
- Otherwise, it is considered a file name.
Use abbreviated file names. For example, an entry \"~/mycode/\" means
that Emacs will trust all the files in your directory \"mycode\".
This variable can also be set to `:all', in which case Emacs will trust
all files, which opens a gaping security hole. Emacs Lisp authors
should note that this value must never be set by a major or minor mode."
:type '(choice (repeat :tag "List" file)
(const :tag "Trust everything (DANGEROUS!)" :all))
:version "30.1")
(put 'trusted-content 'risky-local-variable t)
(defun trusted-content-p ()
"Return non-nil if we trust the contents of the current buffer.
Here, \"trust\" means that we are willing to run code found inside of it.
See also `trusted-content'."
;; We compare with `buffer-file-truename' i.s.o `buffer-file-name'
;; to try and avoid marking as trusted a file that's merely accessed
;; via a symlink that happens to be inside a trusted dir.
(and (not untrusted-content)
(or
(eq trusted-content :all)
(and
buffer-file-truename
(with-demoted-errors "trusted-content-p: %S"
(let ((exists (file-exists-p buffer-file-truename)))
(or
;; We can't avoid trusting the user's init file.
(if (and exists user-init-file)
(file-equal-p buffer-file-truename user-init-file)
(equal buffer-file-truename user-init-file))
(let ((file (abbreviate-file-name buffer-file-truename))
(trusted nil))
(dolist (tf trusted-content)
(when (or (if exists (file-equal-p tf file) (equal tf file))
;; We don't use `file-in-directory-p' here, because
;; we want to err on the conservative side: "guilty
;; until proven innocent".
(and (string-suffix-p "/" tf)
(string-prefix-p tf file)))
(setq trusted t)))
trusted))))))))
;; This is an odd variable IMO.
;; You might wonder why it is needed, when we could just do:
;; (setq-local 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.
(defvar local-enable-local-variables t
"Like `enable-local-variables', except for major mode in a -*- line.
The meaningful values are nil and non-nil. The default is non-nil.
It should be set in a buffer-local fashion.
Setting this to nil has the same effect as setting `enable-local-variables'
to nil, except that it does not ignore any mode: setting in a -*- line.
Unless this difference matters to you, you should set `enable-local-variables'
instead of this variable.")
(defcustom enable-local-eval 'maybe
"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.
A value of nil means ignore them; anything else means query."
:risky t
:type '(choice (const :tag "Obey" t)
(const :tag "Ignore" nil)
(other :tag "Query" other))
:group 'find-file)
(defcustom view-read-only nil
"Non-nil means buffers visiting files read-only do so in view mode.
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 \\[read-only-mode]."
:type 'boolean
:group 'view)
(defvar file-name-history nil
"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.")
(defvar save-silently nil
"If non-nil, avoid messages when saving files.
Error-related messages will still be printed, but all other
messages will not.")
(put 'ange-ftp-completion-hook-function 'safe-magic t)
(defun ange-ftp-completion-hook-function (op &rest args)
"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.
(if (memq op '(file-name-completion file-name-all-completions))
(apply 'ange-ftp-hook-function op args)
(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))
(apply op args))))
(declare-function dos-convert-standard-filename "dos-fns.el" (filename))
(declare-function w32-convert-standard-filename "w32-fns.el" (filename))
(defun convert-standard-filename (filename)
"Convert a standard file's name to something suitable for the OS.
This means to guarantee valid names and perhaps to canonicalize
certain patterns.
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.
This function's standard definition is trivial; it just returns
the argument. However, on Windows and DOS, replace invalid
characters. On DOS, make sure to obey the 8.3 limitations.
In the native Windows build, turn Cygwin names into native names.
See Info node `(elisp)Standard File Names' for more details."
(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)))
(defun read-directory-name (prompt &optional dir default-dirname mustmatch initial predicate)
"Read directory name, prompting with PROMPT and completing in directory DIR.
The return value is not expanded---you must call `expand-file-name'
yourself.
DIR is the directory to use for completing relative file names.
It should be an absolute directory name, or nil (which means the
current buffer's value of `default-directory').
DEFAULT-DIRNAME specifies the default directory name to return if user
exits with the same non-empty string that was inserted by this function.
(If DEFAULT-DIRNAME is omitted, DIR combined with INITIAL is used,
or just DIR if INITIAL is nil.)
Return the directory as a string.
If the user exits with an empty minibuffer, return an empty
string. (This can happen only if the user erased the pre-inserted
contents or if `insert-default-directory' is nil.)
Fourth arg MUSTMATCH, is like for `read-file-name', which see.
Fifth arg INITIAL specifies text to start with.
Sixth arg PREDICATE, if non-nil, should be a function of one
argument; then a directory is considered an acceptable completion
alternative only if PREDICATE returns non-nil with the file name
as its argument."
(unless dir
(setq dir default-directory))
(read-file-name prompt dir (or default-dirname
(if initial (expand-file-name initial dir)
dir))
mustmatch initial
(if predicate
(lambda (filename)
(and (file-directory-p filename)
(funcall predicate filename)))
#'file-directory-p)))
(defun pwd (&optional insert)
"Show the current default directory.
With prefix argument INSERT, insert the current default directory
at point instead."
(interactive "P")
(if insert
(insert default-directory)
(message "Directory %s" default-directory)))
(defvar cd-path nil
"Value of the CDPATH environment variable, as a list.
Not actually set up until the first time you use it.")
(defun parse-colon-path (search-path)
"Explode a search path into a list of directory names.
Directories are separated by `path-separator' (which is colon in
GNU and Unix systems). Substitute environment variables into the
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."
(declare (ftype (function (string) list)))
(when (stringp search-path)
(let ((spath (substitute-env-vars search-path))
(double-slash-special-p
(memq system-type '(windows-nt cygwin ms-dos))))
(mapcar (lambda (f)
(if (equal "" f) nil
(let ((dir (file-name-as-directory f)))
;; Previous implementation used `substitute-in-file-name'
;; which collapses multiple "/" in front, while
;; preserving double slash where it matters. Do
;; the same for backward compatibility.
(if (string-match "\\`//+" dir)
(substring dir (- (match-end 0)
(if double-slash-special-p 2 1)))
dir))))
(split-string spath path-separator)))))
(defun cd-absolute (dir)
"Change current directory to given absolute file name DIR."
;; Put the name into directory syntax now,
;; because otherwise expand-file-name may give some bad results.
(setq dir (file-name-as-directory dir))
;; 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))
(if (not (file-directory-p dir))
(error (if (file-exists-p dir)
"%s is not a directory"
"%s: no such directory")
dir)
(unless (file-accessible-directory-p dir)
(error "Cannot cd to %s: Permission denied" dir))
(setq default-directory dir)
(setq list-buffers-directory dir)))
(defun cd (dir)
"Make DIR become the current buffer's default directory.
If your environment includes a `CDPATH' variable, try each one of
that list of directories (separated by occurrences of
`path-separator') when resolving a relative directory name.
The path separator is colon in GNU and GNU-like systems."
(interactive
(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-local minibuffer-completion-table
(apply-partially #'locate-file-completion-table
cd-path nil))
(setq-local minibuffer-completion-predicate
(lambda (dir)
(locate-file dir cd-path nil