file local variables

file local variables

[Francesc Rocher]

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Hi,

File local variables doesn't work as expected. If you 'emacs -Q' a file with

Local Variables:
mode: text
mode: auto-fill
End:

or with any other combination of a major and a minor mode, then the major
mode is ignored. Is this a bug? This works fine with emacs-23.1, where both
modes are activated...

-- rocher

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Re: file local variables

[Juri Linkov]

> File local variables doesn't work as expected. If you 'emacs -Q' a file with
>
> Local Variables:
> mode: text
> mode: auto-fill
> End:
>
> or with any other combination of a major and a minor mode, then the major
> mode is ignored. Is this a bug? This works fine with emacs-23.1, where both
> modes are activated...

(info "(emacs) Specifying File Variables") says:

     You can use the `mode' "variable" to set minor modes as well as the
  major modes; in fact, you can use it more than once, first to set the
  major mode and then to set minor modes which are specific to particular
  buffers.  But most minor modes should not be specified in the file at
  all, because they represent user preferences.

Since the user should be able to specify minor modes more than once,
the following patch fixes this by allowing duplicate modes:

=== modified file 'lisp/files.el'
--- lisp/files.el	2009-11-25 17:11:29 +0000
+++ lisp/files.el	2009-12-14 21:28:58 +0000
@@ -2978,8 +2978,8 @@
 		 (or (eq enable-local-eval t)
 		     (hack-one-local-variable-eval-safep (eval (quote val)))
 		     (push elt unsafe-vars))))
-	      ;; Ignore duplicates in the present list.
-	      ((assq var all-vars) nil)
+	      ;; Ignore duplicates (except `mode') in the present list.
+	      ((and (assq var all-vars) (not (eq var 'mode))) nil)
 	      ;; Accept known-safe variables.
 	      ((or (memq var '(mode unibyte coding))
 		   (safe-local-variable-p var val))
@@ -2999,7 +2999,7 @@
 	     (hack-local-variables-confirm all-vars unsafe-vars
 					   risky-vars dir-name))
 	 (dolist (elt all-vars)
-	   (unless (eq (car elt) 'eval)
+	   (unless (memq (car elt) '(eval mode))
 	     (unless dir-name
 	       (setq dir-local-variables-alist
 		     (assq-delete-all (car elt) dir-local-variables-alist)))
@@ -3427,7 +3427,7 @@
 		(dir-locals-get-class-variables class) dir-name nil)))
 	  (when variables
 	    (dolist (elt variables)
-	      (unless (eq (car elt) 'eval)
+	      (unless (memq (car elt) '(eval mode))
 		(setq dir-local-variables-alist
 		      (assq-delete-all (car elt) dir-local-variables-alist)))
 	      (push elt dir-local-variables-alist))

-- 
Juri Linkov
http://www.jurta.org/emacs/

Re: file local variables

[Juri Linkov]

BTW, while looking at this bug, I noticed a security hole in using
duplicate file local variables.

`hack-local-variables-filter' checks for the safety the value of the *last*
duplicate local variable in the list (the first in the reversed list), but
`hack-local-variables' uses an unchecked value of the *first* duplicate
local variable.

-- 
Juri Linkov
http://www.jurta.org/emacs/

Re: file local variables

[Francesc Rocher]

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> Since the user should be able to specify minor modes more than once,
> the following patch fixes this by allowing duplicate modes:
>


Thanks,  your patch works fine.

-- Rocher

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Re: file local variables

[Juri Linkov]

> BTW, while looking at this bug, I noticed a security hole in using
> duplicate file local variables.
>
> `hack-local-variables-filter' checks for the safety the value of the *last*
> duplicate local variable in the list (the first in the reversed list), but
> `hack-local-variables' uses an unchecked value of the *first* duplicate
> local variable.

Hopefully, this is a false alarm.  I can't find a recipe to reproduce this.

-- 
Juri Linkov
http://www.jurta.org/emacs/

Re: file local variables

[Juri Linkov]

>> BTW, while looking at this bug, I noticed a security hole in using
>> duplicate file local variables.
>>
>> `hack-local-variables-filter' checks for the safety the value of the *last*
>> duplicate local variable in the list (the first in the reversed list), but
>> `hack-local-variables' uses an unchecked value of the *first* duplicate
>> local variable.
>
> Hopefully, this is a false alarm.  I can't find a recipe to reproduce this.

Sometimes it's even more safe than necessary.  When .dir-locals.el
contains a variable with an unsafe value, but file-local variables contain
a safe value of the same variable, it asks confirmation for the unsafe
directory-local value, but really uses the safe file-local variable's value.

I think this is not a problem.  It seems better to remind the user that
.dir-locals.el contains an unsafe value.

-- 
Juri Linkov
http://www.jurta.org/emacs/