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(file-truename): Use iteration when possible.

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Avoid recalculating the same truename twice in one invocation.
Error check for infinite link loop.

(debugger): Make it a risky-local-variable.
This commit is contained in:
Richard M. Stallman 1994-07-05 20:23:13 +00:00
parent 30dc01ea24
commit 05ef1cdab9
1 changed files with 64 additions and 33 deletions
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97
lisp/files.el
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@ -329,11 +329,18 @@ accessible."
(funcall handler 'file-local-copy file)
nil)))
(defun file-truename (filename)
(defun file-truename (filename &optional counter prev-dirs)
"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
containing it, until no links are left at any level."
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.
(if (or (string= filename "~")
(and (string= (substring filename 0 1) "~")
(string-match "~[^/]*" filename)))
@ -341,37 +348,60 @@ containing it, until no links are left at any level."
(setq filename (expand-file-name filename))
(if (string= filename "")
(setq 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
(funcall handler 'file-truename filename)
(let ((dir (file-name-directory filename))
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)
(setq dir (file-name-as-directory (file-truename dirfile))))
(if (equal ".." (file-name-nondirectory filename))
(directory-file-name (file-name-directory (directory-file-name dir)))
(if (equal "." (file-name-nondirectory filename))
(directory-file-name dir)
;; 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.
(if (file-name-absolute-p target)
(file-truename target)
(file-truename (concat dir target)))
;; No, we are done!
filename)))))))
(or counter (setq counter (list 100)))
(or prev-dirs (setq prev-dirs (list nil)))
(let (done)
;; 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)
(let ((dir (file-name-directory filename))
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))
(defun file-chase-links (filename)
"Chase links in FILENAME until a name that is not a link.
@ -1105,6 +1135,7 @@ If `enable-local-variables' is nil, this function does not check for a
"Variables to be ignored in a file's local variable spec.")
;; Get confirmation before setting these variables as locals in a file.
(put 'debugger 'risky-local-variable t)
(put 'enable-local-eval 'risky-local-variable t)
(put 'eval 'risky-local-variable t)
(put 'file-name-handler-alist 'risky-local-variable t)