Re: Error with tramp-archive-autoload-file-name-handler

[Michael Albinus <michael.albinus@gmx.de>]

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Felix Dietrich <felix.dietrich@sperrhaken.name> writes:

Hi,

> Michael Heerdegen <michael_heerdegen@web.de> writes:
>
>> Michael Albinus <michael.albinus@gmx.de> writes:
>>
>>> I cannot reproduce. The following works fine:
>>>
>>> […]
>>
>> You missed the TWICE part in my last message.  Just eval the above
>> twice:
>>
>> $ emacs -Q -l tramp --eval "(add-to-list 'file-name-handler-alist
>> (cons (tramp-archive-autoload-file-name-regexp)
>> #'tramp-archive-autoload-file-name-handler))" --eval
>> '(file-directory-p "/home/albinus/tmp/out.tar.xz/")'\
>>                     --eval "(add-to-list 'file-name-handler-alist
>> (cons (tramp-archive-autoload-file-name-regexp)
>> #'tramp-archive-autoload-file-name-handler))" --eval
>> '(file-directory-p "/home/albinus/tmp/out.tar.xz/")'
>>
>> Sorry, but that's the best recipe I can offer.  And I guess something
>> like this is actually happening.  AFAIU, Tramp can call
>> `tramp-register-archive-file-name-handler' several times - see
>> tramp-archive.el line 394:
>
> With Emacs 27.1, I ran the test in the attached script a couple of times
> and could *not* reproduce your error.

Same here, I cannot reproduce it with Emacs 27, Emacs 28, Emacs 29. Btw,
I believe a more realistic check would be

--8<---------------cut here---------------start------------->8---
$ emacs -Q -f tramp-register-archive-file-name-handler --eval '(file-directory-p "/home/albinus/tmp/out.tar.xz/")'\
           -f tramp-register-archive-file-name-handler --eval '(file-directory-p "/home/albinus/tmp/out.tar.xz/")'
--8<---------------cut here---------------end--------------->8---

It is tramp-register-archive-file-name-handler which might be invoked
several times, and which causes the problem. Could *you* (Michael)
reproduce the problem with this recipe?

Anyway, I've pushed the appended patch to the repositories. It should fix
this problem, hopefully.

Best regards, Michael.


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diff --git a/lisp/net/tramp-archive.el b/lisp/net/tramp-archive.el
index 788e457367..890c8dbb75 100644
--- a/lisp/net/tramp-archive.el
+++ b/lisp/net/tramp-archive.el
@@ -374,7 +374,9 @@ tramp-archive-file-name-handler
 ;;;###autoload
 (progn (defun tramp-register-archive-file-name-handler ()
   "Add archive file name handler to `file-name-handler-alist'."
-  (when tramp-archive-enabled
+  (when (and tramp-archive-enabled
+             (not
+              (rassq #'tramp-archive-file-name-handler file-name-handler-alist)))
     (add-to-list 'file-name-handler-alist
                 (cons (tramp-archive-autoload-file-name-regexp)
                       #'tramp-archive-autoload-file-name-handler))
diff --git a/lisp/net/tramp.el b/lisp/net/tramp.el
index 0192a63a10..580cfea1f8 100644
--- a/lisp/net/tramp.el
+++ b/lisp/net/tramp.el
@@ -2756,10 +2756,11 @@ tramp-completion-file-name-handler
 ;;;###autoload
 (progn (defun tramp-register-autoload-file-name-handlers ()
   "Add Tramp file name handlers to `file-name-handler-alist' during autoload."
-  (add-to-list 'file-name-handler-alist
-              (cons tramp-autoload-file-name-regexp
-                    #'tramp-autoload-file-name-handler))
-  (put #'tramp-autoload-file-name-handler 'safe-magic t)))
+  (unless (rassq #'tramp-file-name-handler file-name-handler-alist)
+    (add-to-list 'file-name-handler-alist
+                (cons tramp-autoload-file-name-regexp
+                      #'tramp-autoload-file-name-handler))
+    (put #'tramp-autoload-file-name-handler 'safe-magic t))))

 (put #'tramp-register-autoload-file-name-handlers 'tramp-autoload t)
 ;;;###autoload (tramp-register-autoload-file-name-handlers)