Function: make-auto-save-file-name

make-auto-save-file-name is a byte-compiled function defined in files.el.gz.

Signature

(make-auto-save-file-name)

Documentation

Return file name to use for auto-saves of current buffer.

Does not consider auto-save-visited-file-name as that variable is checked before calling this function. See also auto-save-file-name-p.

View in manual

Probably introduced at or before Emacs version 1.6.

Source Code

;; Defined in /usr/src/emacs/lisp/files.el.gz
(defun make-auto-save-file-name ()
  "Return file name to use for auto-saves of current buffer.
Does not consider `auto-save-visited-file-name' as that variable is checked
before calling this function.
See also `auto-save-file-name-p'."
  (if buffer-file-name
      (let ((handler (find-file-name-handler
                      buffer-file-name 'make-auto-save-file-name)))
	(if handler
	    (funcall handler 'make-auto-save-file-name)
          (files--transform-file-name
           buffer-file-name auto-save-file-name-transforms
                                          "#" "#")))
    ;; Deal with buffers that don't have any associated files.  (Mail
    ;; mode tends to create a good number of these.)
    (let ((buffer-name (buffer-name))
	  (limit 0)
	  file-name)
      ;; Restrict the characters used in the file name to those that
      ;; are known to be safe on all filesystems, url-encoding the
      ;; rest.
      ;; We do this on all platforms, because even if we are not
      ;; running on DOS/Windows, the current directory may be on a
      ;; mounted VFAT filesystem, such as a USB memory stick.
      (while (string-match "[^A-Za-z0-9_.~#+-]" buffer-name limit)
	(let* ((character (aref buffer-name (match-beginning 0)))
	       (replacement
                ;; For multibyte characters, this will produce more than
                ;; 2 hex digits, so is not true URL encoding.
                (format "%%%02X" character)))
	  (setq buffer-name (replace-match replacement t t buffer-name))
	  (setq limit (1+ (match-end 0)))))
      ;; Generate the file name.
      (setq file-name
	    (make-temp-file
	     (let ((fname
		    (expand-file-name
		     (format "#%s#" buffer-name)
		     ;; Try a few alternative directories, to get one we can
		     ;; write it.
		     (cond
		      ((file-writable-p default-directory) default-directory)
		      ((file-writable-p "/var/tmp/") "/var/tmp/")
		      ("~/")))))
	       (if (and (memq system-type '(ms-dos windows-nt cygwin))
			;; Don't modify remote filenames
			(not (file-remote-p fname)))
		   ;; The call to convert-standard-filename is in case
		   ;; buffer-name includes characters not allowed by the
		   ;; DOS/Windows filesystems.  make-temp-file writes to the
		   ;; file it creates, so we must fix the file name _before_
		   ;; make-temp-file is called.
		   (convert-standard-filename fname)
		 fname))
	     nil "#"))
      ;; make-temp-file creates the file,
      ;; but we don't want it to exist until we do an auto-save.
      (condition-case ()
	  (delete-file file-name)
	(file-error nil))
      file-name)))