bug#30724: eshell: escaped tilde is not treated as such

[Noam Postavsky]

Jonathan Kyle Mitchell <kyle@jonathanmitchell.org> writes:

> After tracing through the execution of eshell some more, I noticed that
> eshell sets an escaped text property on the arguments when the user
> escaped them with `\' or quote characters but there is nothing in
> eshell that does anything with it apparently.

Yeah, this sort of half-finished thing seems to pop up in eshell quite a
bit.

> Subject: [PATCH] Check for special filenames in eshell (Bug#30724)
>
>       * lisp/eshell/em-dirs.el (eshell/cd): Add
>       eshell-escape-special-filenames to symbol plist.
>       (eshell/pushd): Likewise.
>       (eshell/popd): Likewise.
>
>       * lisp/eshell/em-ls.el (eshell/ls): Add
>       eshell-escape-special-filenames to symbol plist.
>
>       * lisp/eshell/em-unix.el (eshell/rm): Add
>       eshell-escape-special-filenames to symbol plist.
>       (eshell/mkdir): Likewise.
>       (eshell/rmdir): Likewise.
>       (eshell/mv): Likewise.
>       (eshell/cp): Likewise.
>       (eshell/ln): Likewise.
>       (eshell/cat): Likewise.
>       (eshell/du): Likewise.
>       (eshell/diff): Likewise.
>
>       * lisp/eshell/esh-cmd.el (eshell-lisp-command): Check for
>       single character escaped string arguments (Bug#30724).
>
>       * lisp/eshell/esh-ext.el (eshell/addpath): Add
>       eshell-escape-special-filenames to symbol plist.

The "Add eshell-escape-special-filenames to symbol plist" should be
coalesced, as in:

* lisp/eshell/em-dirs.el (eshell/cd, eshell/pushd, eshell/popd):
* lisp/eshell/em-ls.el (eshell/ls):
* lisp/eshell/em-unix.el (eshell/rm, eshell/mkdir, eshell/rmdir)
(eshell/mv, eshell/cp, eshell/ln, eshell/cat, eshell/du, eshell/diff):
* lisp/eshell/esh-ext.el (eshell/addpath): Add
eshell-escape-special-filenames to symbol plist.

* lisp/eshell/esh-cmd.el (eshell-lisp-command): Check for
single character escaped string arguments (Bug#30724).
  

> +               (let ((numeric (not (get object
> +                                           'eshell-no-numeric-conversions)))
> +                     (escaped (get object 'eshell-escape-special-filenames)))

I'm not sure 'escaped' or 'eshell-escape-special-filenames' are really
the right names here, as they're not actually indicating any escaping.
Maybe the property should be something like 'eshell-filename-arguments'?

> +                 (when (or numeric escaped)
> +                   (while args
> +                     (let ((arg (car args)))
> +                       (cond ((and numeric (stringp arg) (> (length arg) 0)
> +                                   (text-property-any 0 (length arg)
> +                                                      'number t arg))
> +                              ;; if any of the arguments are flagged as
> +                              ;; numbers waiting for conversion, convert
> +                              ;; them now

Comments should be capitalized and end with a period (I know the
original didn't, but since we're updating the code, now is a good time
to fix it).

> +                              (setcar args (string-to-number arg)))
> +                             ((and escaped (stringp arg) (= (length arg) 1)
> +                                   (text-property-any 0 (length arg)
> +                                                      'escaped t arg))
> +                              ;; if any of the arguments are single
> +                              ;; character escaped filenames,
> +                              ;; prepend "./"
> +                              (setcar args (concat "./" arg)))))

It looks like this kind of escaping isn't actually needed for "*" which
your previous patch mentioned.  Perhaps just check for "~" explicitly,
rather than any single character filenames.  Or are there other examples
besides "~" which need "./" to prevent interpretation?