bug#71078: rgrep accepts wildcard, then throws it away

bug#71078: rgrep accepts wildcard, then throws it away

[Dan Jacobson]

When rgrep asks for the Base directory, and the user gives a wildcard,
Base directory: /usr/share/doc/exim4*
it is thrown away, and this instead gets run:
(rgrep "minimaldns" "* .*" "/usr/share/doc/exim4")

In fact this is a very special case, as there happens to be a directory
with just that name,

/usr/share/doc:
  wildcard exim4*
  drwxr-xr-x 2 4096 04-13 07:09 exim4-daemon-light
  drwxr-xr-x 3 4096 04-13 07:09 exim4-base
  drwxr-xr-x 3 4096 04-13 07:09 exim4-config
  drwxr-xr-x 2 4096 2023-11-07  exim4-doc-info
  drwxr-xr-x 3 4096 2023-11-07  exim4-doc-html
  lrwxrwxrwx 1   10 2016-12-08  exim4 -> exim4-base

Normally rgrep won't let the user even proceed if e.g., the user just gave
Base directory: /usr/share/doc/exi*
but in the case where there is in fact a directory that matches exim4,
the "*" gets thrown away!

In fact if we do add the * here,
(rgrep "minimaldns" "* .*" "/usr/share/doc/exim4*")
and do ^X^E, we end up searching ~/ !

emacs-version "29.3"

bug#71078: rgrep accepts wildcard, then throws it away

[Stefan Kangas]

Dan Jacobson <jidanni@jidanni.org> writes:

> When rgrep asks for the Base directory, and the user gives a wildcard,
> Base directory: /usr/share/doc/exim4*
> it is thrown away, and this instead gets run:
> (rgrep "minimaldns" "* .*" "/usr/share/doc/exim4")
>
> In fact this is a very special case, as there happens to be a directory
> with just that name,
>
> /usr/share/doc:
>   wildcard exim4*
>   drwxr-xr-x 2 4096 04-13 07:09 exim4-daemon-light
>   drwxr-xr-x 3 4096 04-13 07:09 exim4-base
>   drwxr-xr-x 3 4096 04-13 07:09 exim4-config
>   drwxr-xr-x 2 4096 2023-11-07  exim4-doc-info
>   drwxr-xr-x 3 4096 2023-11-07  exim4-doc-html
>   lrwxrwxrwx 1   10 2016-12-08  exim4 -> exim4-base
>
> Normally rgrep won't let the user even proceed if e.g., the user just gave
> Base directory: /usr/share/doc/exi*
> but in the case where there is in fact a directory that matches exim4,
> the "*" gets thrown away!

That's just how this call works:

    (read-directory-name "Base directory: "
                         nil default-directory t)

If I give an input like "/tmp* RET" at the prompt, it returns "/tmp/".

What's confusing to me is this part in the docstring of
`read-directory-name':

    Fourth arg MUSTMATCH non-nil means require existing directory’s name.
    Non-nil and non-t means also require confirmation after completion.

I think "require existing directory’s name" should be clarified to say:
"require the user to input an existing directory's name", if that is
indeed the intention here.

That it removes the "*" character seems to be undocumented, but if
that's the intended behaviour perhaps it should be clarified too.  Hmm.

Eli, Stefan, any thoughts here?

> In fact if we do add the * here,
> (rgrep "minimaldns" "* .*" "/usr/share/doc/exim4*")
> and do ^X^E, we end up searching ~/ !

I think this is expected, and not a bug, due to this part in grep.el:

     (unless (and dir (file-accessible-directory-p dir))
       (setq dir default-directory))

I'd rather it would signal an error in this case, to be honest, because
I'm not sure it makes much sense to make the function this DWIM-y.  It'd
be good to hear what other people think about this also.

bug#71078: rgrep accepts wildcard, then throws it away

[Stefan Monnier via Bug reports for GNU Emacs, the Swiss army knife of text editors]

>     (read-directory-name "Base directory: "
>                          nil default-directory t)
>
> If I give an input like "/tmp* RET" at the prompt, it returns "/tmp/".
>
> What's confusing to me is this part in the docstring of
> `read-directory-name':
>
>     Fourth arg MUSTMATCH non-nil means require existing directory’s name.
>     Non-nil and non-t means also require confirmation after completion.
>
> I think "require existing directory’s name" should be clarified to say:
> "require the user to input an existing directory's name", if that is
> indeed the intention here.

That's indeed the intention (and the way I read it, that's what it says).

> That it removes the "*" character seems to be undocumented, but if
> that's the intended behaviour perhaps it should be clarified too.  Hmm.

It does not remove the *.  What you're seeing is the effect of
completion (and `partial-completion` treats the * as a wildcard for
completion purposes) so you can also just type `/tm` and it should
return the same thing (provided `/tmp/` is the sole completion).

> I think this is expected, and not a bug, due to this part in grep.el:
>
>      (unless (and dir (file-accessible-directory-p dir))
>        (setq dir default-directory))
>
> I'd rather it would signal an error in this case, to be honest, because

Agreed.  The above can only make sense when `dir` doesn't matter.


        Stefan