GNU bug report logs - #50189
wdired chmod should not follow symlinks (Bug#11912 followup)

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Message #5 received at submit <at> debbugs.gnu.org (full text, mbox):

From: Paul Eggert <eggert <at> cs.ucla.edu>
To: Emacs bug reports and feature requests <bug-gnu-emacs <at> gnu.org>
Subject: wdired chmod should not follow symlinks
Date: Tue, 24 Aug 2021 11:04:47 -0700

[Message part 1 (text/plain, inline)]

To be consistent with dired M, wdired's method of textually editing a 
symlink's permissions should also not follow symlinks. Proposed patch 
attached.

I did not test this, as I don't use wdired and couldn't get it to work 
for me regardless of whether the patch is applied.

This patch also removes some obsolete commentary about dired-chmod-program.

[0001-Make-wdired-match-dired-with-symlink-permissions.patch (text/x-patch, attachment)]

Message #12 received at 50189 <at> debbugs.gnu.org (full text, mbox):

From: Lars Ingebrigtsen <larsi <at> gnus.org>
To: Paul Eggert <eggert <at> cs.ucla.edu>
Cc: 50189 <at> debbugs.gnu.org
Subject: Re: bug#50189: wdired chmod should not follow symlinks (Bug#11912
 followup)
Date: Wed, 25 Aug 2021 13:47:27 +0200

Paul Eggert <eggert <at> cs.ucla.edu> writes:

> I did not test this, as I don't use wdired and couldn't get it to work
> for me regardless of whether the patch is applied.

Yeah, editing the permissions doesn't seem to work for me in dired.  If
I start with

  -rw-r--r--  1 larsi      larsi       329K Aug 21 18:22 IMG_4478.JPG

and press DEL after the final dash, it'll delete the dash and then say
"Text is read only", leaving me with:

  -rw-r--r-  1 larsi      larsi       329K Aug 21 18:22 IMG_4478.JPG

And then I can't insert anything there, because it's now read-only.  So
something is wonky in the way wdired tries to make certain bits of the
line read-only.

-- 
(domestic pets only, the antidote for overdose, milk.)
   bloggy blog: http://lars.ingebrigtsen.no

Message #15 received at 50189 <at> debbugs.gnu.org (full text, mbox):

From: Lars Ingebrigtsen <larsi <at> gnus.org>
To: Paul Eggert <eggert <at> cs.ucla.edu>
Cc: 50189 <at> debbugs.gnu.org
Subject: Re: bug#50189: wdired chmod should not follow symlinks (Bug#11912
 followup)
Date: Sat, 10 Sep 2022 08:21:03 +0200

Paul Eggert <eggert <at> cs.ucla.edu> writes:

> To be consistent with dired M, wdired's method of textually editing a
> symlink's permissions should also not follow symlinks. Proposed patch
> attached.

The patch looks "obviously correct", so I've applied it to Emacs 29.

Message #18 received at 50189 <at> debbugs.gnu.org (full text, mbox):

From: Lars Ingebrigtsen <larsi <at> gnus.org>
To: Paul Eggert <eggert <at> cs.ucla.edu>
Cc: 50189 <at> debbugs.gnu.org
Subject: Re: bug#50189: wdired chmod should not follow symlinks (Bug#11912
 followup)
Date: Sat, 10 Sep 2022 08:28:02 +0200

Lars Ingebrigtsen <larsi <at> gnus.org> writes:

> Yeah, editing the permissions doesn't seem to work for me in dired.  If
> I start with
>
>   -rw-r--r--  1 larsi      larsi       329K Aug 21 18:22 IMG_4478.JPG
>
> and press DEL after the final dash, it'll delete the dash and then say
> "Text is read only", leaving me with:
>
>   -rw-r--r-  1 larsi      larsi       329K Aug 21 18:22 IMG_4478.JPG
>
> And then I can't insert anything there, because it's now read-only.  So
> something is wonky in the way wdired tries to make certain bits of the
> line read-only.

Setting wdired-allow-to-change-permissions to t or `advanced' made this
work -- you can't really edit the permissions without that.

So I guess there's nothing more to be done here...

Message #23 received at 50189 <at> debbugs.gnu.org (full text, mbox):

From: Michael Heerdegen <michael_heerdegen <at> web.de>
To: Lars Ingebrigtsen <larsi <at> gnus.org>
Cc: 50189 <at> debbugs.gnu.org, Paul Eggert <eggert <at> cs.ucla.edu>,
 Arthur Miller <arthur.miller <at> live.com>
Subject: Re: bug#50189: wdired chmod should not follow symlinks (Bug#11912
 followup)
Date: Sun, 11 Sep 2022 03:32:42 +0200

Lars Ingebrigtsen <larsi <at> gnus.org> writes:

> Lars Ingebrigtsen <larsi <at> gnus.org> writes:
>
> > Yeah, editing the permissions doesn't seem to work for me in dired.  If
> > I start with
> >
> >   -rw-r--r--  1 larsi      larsi       329K Aug 21 18:22 IMG_4478.JPG
> >
> > and press DEL after the final dash, it'll delete the dash and then say
> > "Text is read only", leaving me with:
> >
> >   -rw-r--r-  1 larsi      larsi       329K Aug 21 18:22 IMG_4478.JPG
> >
> > And then I can't insert anything there, because it's now read-only.  So
> > something is wonky in the way wdired tries to make certain bits of the
> > line read-only.
>
> Setting wdired-allow-to-change-permissions to t or `advanced' made this
> work -- you can't really edit the permissions without that.

That behavior not optimal and a bit confusing.

As you might remember, text properties in wdired are now attached on the
fly for better performance, implemented here:

| 4dbc44550d * lisp/wdired.el: Apply text properties lazily
| Arthur Miller <arthur.miller <at> live.com> 2021-03-27

[Arthur is CC'd]

The problem in this case: the read-only property is attached in
`before-change-functions'.  But that doesn't prevent the change being
performed.  Try e.g. in *scratch*:

#+begin_src emacs-lisp
(add-hook 'before-change-functions
          (lambda (&rest _)
            (put-text-property (point-min) (point-max)
                               'read-only t))
          nil t)
#+end_src

The first changes goes through although the text is already read-only,
because it's still the same command or so (anyone thinking this is a
bug?).

I think we could make wdired explicitly check for and throw a
"user-error" in this case so that the editing command is not performed
(but only after the properties were attached).

TIA,

Michael.

Message #26 received at 50189 <at> debbugs.gnu.org (full text, mbox):

From: Lars Ingebrigtsen <larsi <at> gnus.org>
To: Michael Heerdegen <michael_heerdegen <at> web.de>
Cc: 50189 <at> debbugs.gnu.org, Paul Eggert <eggert <at> cs.ucla.edu>,
 Arthur Miller <arthur.miller <at> live.com>
Subject: Re: bug#50189: wdired chmod should not follow symlinks (Bug#11912
 followup)
Date: Sun, 11 Sep 2022 13:05:32 +0200

Michael Heerdegen <michael_heerdegen <at> web.de> writes:

>> Setting wdired-allow-to-change-permissions to t or `advanced' made this
>> work -- you can't really edit the permissions without that.
>
> That behavior not optimal and a bit confusing.

Yeah, like a lot of stuff with dired and wdired, unfortunately.

> I think we could make wdired explicitly check for and throw a
> "user-error" in this case so that the editing command is not performed
> (but only after the properties were attached).

You mean in the wdired-allow-to-change-permissions nil case?  Yes,
definitely.

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