Re: /srv/bzr/emacs/trunk r100059: (bug-reference-url-format): Mark as `safe-local-variable' if the value

Re: /srv/bzr/emacs/trunk r100059: (bug-reference-url-format): Mark as `safe-local-variable' if the value

[Glenn Morris]

Sam Steingold wrote:

> +2010-04-27  Sam Steingold  <sds@gnu.org>
> +
> +	* progmodes/bug-reference.el (bug-reference-url-format): Mark as
> +	`safe-local-variable' if the value is a string or a function,

I'm probably being thick, but I don't see how an arbitrary function
can be assumed to be safe. Eg consider a ChangeLog file:


2010-04-27  A N Other  <none@example.com>

    * configure.in: Blah. (Bug#123)

;; Local Variables:
;; mode: bug-reference
;; bug-reference-url-format: (lambda () (shell-command "touch /tmp/foo"))
;; End:


Optionally, replace "touch /tmp/foo" with "rm -rf ~".

Re: /srv/bzr/emacs/trunk r100059: (bug-reference-url-format): Mark as `safe-local-variable' if the value

[Chong Yidong]

Glenn Morris <rgm@gnu.org> writes:

> 2010-04-27  A N Other  <none@example.com>
>
>     * configure.in: Blah. (Bug#123)
>
> ;; Local Variables:
> ;; mode: bug-reference
> ;; bug-reference-url-format: (lambda () (shell-command "touch /tmp/foo"))
> ;; End:
>
> Optionally, replace "touch /tmp/foo" with "rm -rf ~".

I think the canonical operation is "launch missiles".

Re: /srv/bzr/emacs/trunk r100059: (bug-reference-url-format): Mark as `safe-local-variable' if the value

[Sam Steingold]

On 4/27/10, Glenn Morris <rgm@gnu.org> wrote:
> Sam Steingold wrote:
>
>  > +2010-04-27  Sam Steingold  <sds@gnu.org>
>  > +
>  > +     * progmodes/bug-reference.el (bug-reference-url-format): Mark as
>  > +     `safe-local-variable' if the value is a string or a function,
>
>  I'm probably being thick, but I don't see how an arbitrary function
>  can be assumed to be safe

You are right.
this means that I cannot really set bug-reference-url-format in the
"Local Variables:"
section together with "mode: bug-reference" if I also set
enable-local-variables to :safe.
if I set it to "t", I get asked about local variable for _every_ file
operation (including diff!)
in the emacs tree and anything else ignores my local settings of
bug-reference-url-format.

For your reference, I set bug-reference-url-format to
clisp-bug-reference-url-format:

(defun clisp-bug-reference-url-format ()
 (concat "http://sourceforge.net/tracker/index.php?func=detail&aid="
         (match-string-no-properties 2)
         "&group_id=1355&atid="
         (let ((kind (match-string-no-properties 1)))
           (cond ((string-match "[Bb]ug" kind) "101355")
                 ((string-match "[Pp]atch" kind) "301355")
                 ((string-match "RFE" kind) "351355")
                 (t (error "unknown bug kind [%s]" kind))))))

I expect this kind of setting to be fairly common unless one is using
the gnu bug tracker or something similar.

the bottom line is that there _must_ be a way to use something
reasonably flexible here and still not be asked "local variable"
question for each C-x v =

-- 
Sam Steingold <http://sds.podval.org>

Re: /srv/bzr/emacs/trunk r100059: (bug-reference-url-format): Mark as `safe-local-variable' if the value

[Lennart Borgman]

On Wed, Apr 28, 2010 at 12:09 AM, Sam Steingold <sds@gnu.org> wrote:
> On 4/27/10, Glenn Morris <rgm@gnu.org> wrote:
>> Sam Steingold wrote:
>>
>>  > +2010-04-27  Sam Steingold  <sds@gnu.org>
>>  > +
>>  > +     * progmodes/bug-reference.el (bug-reference-url-format): Mark as
>>  > +     `safe-local-variable' if the value is a string or a function,
>>
>>  I'm probably being thick, but I don't see how an arbitrary function
>>  can be assumed to be safe
>
> You are right.
> this means that I cannot really set bug-reference-url-format in the
> "Local Variables:"
> section together with "mode: bug-reference" if I also set
> enable-local-variables to :safe.
...
> the bottom line is that there _must_ be a way to use something
> reasonably flexible here and still not be asked "local variable"
> question for each C-x v =


Maybe a safe value could be a (symbol) key to an association lists
with entries like '(my-key my-bug-reference-url-function)?

Re: /srv/bzr/emacs/trunk r100059: (bug-reference-url-format): Mark as `safe-local-variable' if the value

[Chong Yidong]

Sam Steingold <sds@gnu.org> writes:

> this means that I cannot really set bug-reference-url-format in the
> "Local Variables:"
> section together with "mode: bug-reference" if I also set
> enable-local-variables to :safe.
>
> For your reference, I set bug-reference-url-format to
> clisp-bug-reference-url-format:
>
> (defun clisp-bug-reference-url-format ()
>  (concat "http://sourceforge.net/tracker/index.php?func=detail&aid="
>          (match-string-no-properties 2)
>          "&group_id=1355&atid="
>          (let ((kind (match-string-no-properties 1)))
>            (cond ((string-match "[Bb]ug" kind) "101355")
>                  ((string-match "[Pp]atch" kind) "301355")
>                  ((string-match "RFE" kind) "351355")
>                  (t (error "unknown bug kind [%s]" kind))))))

Where do you define clisp-bug-reference-url-format?  In your init file?
If so, you could probably add

  (put 'bug-reference-url-format 'safe-local-variable
       (lambda (s) (or (stringp s)
                       (eq s 'clisp-bug-reference-url-format))))

at the same place.

Re: /srv/bzr/emacs/trunk r100059: (bug-reference-url-format): Mark as `safe-local-variable' if the value

[Sam Steingold]

On 4/27/10, Chong Yidong <cyd@stupidchicken.com> wrote:
> Sam Steingold <sds@gnu.org> writes:
>
>  > this means that I cannot really set bug-reference-url-format in the
>  > "Local Variables:"
>  > section together with "mode: bug-reference" if I also set
>  > enable-local-variables to :safe.
>  >
>
> > For your reference, I set bug-reference-url-format to
>  > clisp-bug-reference-url-format:
>  >
>  > (defun clisp-bug-reference-url-format ()
>  >  (concat "http://sourceforge.net/tracker/index.php?func=detail&aid="
>  >          (match-string-no-properties 2)
>  >          "&group_id=1355&atid="
>  >          (let ((kind (match-string-no-properties 1)))
>  >            (cond ((string-match "[Bb]ug" kind) "101355")
>  >                  ((string-match "[Pp]atch" kind) "301355")
>  >                  ((string-match "RFE" kind) "351355")
>  >                  (t (error "unknown bug kind [%s]" kind))))))
>
>
> Where do you define clisp-bug-reference-url-format?  In your init file?

no, it is a part of the clisp distribution (and cvs tree)

>  If so, you could probably add
>
>   (put 'bug-reference-url-format 'safe-local-variable
>        (lambda (s) (or (stringp s)
>                        (eq s 'clisp-bug-reference-url-format))))
>
>  at the same place.
>

brilliant!
actually, I think the right way is

(put 'bug-reference-url-format 'safe-local-variable
  (let ((f (get 'bug-reference-url-format 'safe-local-variable)))
   (lambda (s) (or (funcall f s) (eq s 'clisp-bug-reference-url-format)))))

so that if others do that too, I will not override them.
in fact, maybe the above should be a standard function
(add-safe-value variable symbol)

-- 
Sam Steingold <http://sds.podval.org>

Re: /srv/bzr/emacs/trunk r100059: (bug-reference-url-format): Mark as `safe-local-variable' if the value

[Davis Herring]

> (put 'bug-reference-url-format 'safe-local-variable
>   (let ((f (get 'bug-reference-url-format 'safe-local-variable)))
>    (lambda (s) (or (funcall f s) (eq s
> 'clisp-bug-reference-url-format)))))

That won't work if the existing value is not a function (e.g. if it is t
(which would be foolish, of course) or nil).  Moreover, you need to use
backquotes: (let ((f ...)) `(lambda (s) (or (funcall ,f s) ...))) (this is
one of the reasons people want lexbind).

> so that if others do that too, I will not override them.
> in fact, maybe the above should be a standard function
> (add-safe-value variable symbol)

I don't know how often it is useful to be able to add many individual safe
values for a variable; perhaps instead there should be another variable
whose file-local value can be a string s from which
`bug-reference-url-format' is calculated as (intern (concat s
"-url-format")).  Then only functions intended for the purpose could be
selected by the file.

Or, more generally, perhaps there should be a symbol property
`safe-file-function' placed on symbols whose values as functions were safe
to call regardless of context, so that we could then allow precisely those
symbols as the values of certain function-valued file locals:

(put 'clisp-bug-reference-url-format 'safe-file-function t)
(defun safe-file-function-p (f)
  (and (symbolp f) (get f 'safe-file-function))
(put 'bug-reference-url-format 'safe-local-variable 'safe-file-function-p)

Davis

-- 
This product is sold by volume, not by mass.  If it appears too dense or
too sparse, it is because mass-energy conversion has occurred during
shipping.

Re: /srv/bzr/emacs/trunk r100059: (bug-reference-url-format): Mark as `safe-local-variable' if the value

[Chong Yidong]

"Davis Herring" <herring@lanl.gov> writes:

>> (put 'bug-reference-url-format 'safe-local-variable
>>   (let ((f (get 'bug-reference-url-format 'safe-local-variable)))
>>    (lambda (s) (or (funcall f s) (eq s
>> 'clisp-bug-reference-url-format)))))
>
> That won't work if the existing value is not a function (e.g. if it is t
> (which would be foolish, of course) or nil).

A `safe-local-variable' property must be a function of one argument
(or nil).

Re: /srv/bzr/emacs/trunk r100059: (bug-reference-url-format): Mark as `safe-local-variable' if the value

[Davis Herring]

> A `safe-local-variable' property must be a function of one argument
> (or nil).

Ah, sorry; I don't know why I thought t was allowed.  But the code I was
commenting on would fail with nil too, as I said, so the point remains.

While reading further I also see that we already have
`safe-local-variable-values' for the case where particular values need to
be marked as safe, which certainly satisfies the stated desire to allow
one additional value for a variable without the `lambda' trickery. 
Perhaps the `safe-file-function' property would nonetheless be useful to
avoid having to add many different things to s-l-v-v.

Davis

-- 
This product is sold by volume, not by mass.  If it appears too dense or
too sparse, it is because mass-energy conversion has occurred during
shipping.

Re: /srv/bzr/emacs/trunk r100059: (bug-reference-url-format): Mark as `safe-local-variable' if the value

[Chong Yidong]

"Davis Herring" <herring@lanl.gov> writes:

> While reading further I also see that we already have
> `safe-local-variable-values' for the case where particular values need to
> be marked as safe, which certainly satisfies the stated desire to allow
> one additional value for a variable without the `lambda' trickery.
> Perhaps the `safe-file-function' property would nonetheless be useful to
> avoid having to add many different things to s-l-v-v.

It's not practical for an external package to change
safe-local-variable-values, because that is a customizable user option.