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bug#24576: 25.1; desktop.el does not fully preserve registers with macro
bug#24576: 25.1; desktop.el does not fully preserve registers with macros
Wed, 22 May 2019 23:43:12 -0400
Gnus/5.13 (Gnus v5.13) Emacs/26.2 (gnu/linux)
Matthew Newton <address@hidden> writes:
> (defun desktop--v2s (value)
> ((byte-code-function-p value)
> (let* ((pass1 (mapcar #'desktop--v2s value))
> (special (assq nil pass1)))
> (if special
> (cons nil `(make-byte-code
> ,@(mapcar (lambda (el)
> (if (eq (car el) 'must)
> `',(cdr el) (cdr el)))
> (cons 'may `[,@(mapcar #'cdr pass1)]))))
I don't think `[...] will ever return a byte code function, so the
non-special case doesn't seem quite right.
> Are there security concerns or other considerations?
Well, as (info "(elisp) Byte-Code Objects") mentions, passing the wrong
args to make-byte-code can produce a function which will crash Emacs
when called, so it's somewhat high risk.
>> The "unprintable entity" comes from desktop--v2s, looks like it doesn't
>> handle compiled function values, so that's why :print-func and
>> :insert-func get messed up like that.
I note that the functions in question come from this code in kmacro.el:
(defun kmacro-to-register (r)
:print-func (lambda (k)
(princ (format "a keyboard macro:\n %s"
:insert-func (lambda (k)
(insert (format-kbd-macro k))))
While in register.el we have:
(cl-defun registerv-make (data &key print-func jump-func insert-func)
(declare (obsolete "Use your own type with methods on
So perhaps this is a good opportunity to change the kmacro register
stuff to use the non-obsolete way.
>>> I’ve also seen “Unprintable entity” show up when a buffer position
>>> register points to a nonexistent buffer. Not sure how to reproduce
>>> that one.
>> I guess if you save a position in a buffer, then kill the buffer.
> Here is what I found: if the killed buffer visits a file, it gets
> converted into a file-query. If there is no `buffer-file-name` then it
> stays a file marker pointing to nowhere. Desktop handles both of those
> cases correctly. So while I have seen it happen I’m not sure of the
> case where a buffer position register becomes an “Unprintable
> entity”. Did you find reproduction steps?
Ah, no, I was just guessing based on your initial description, no idea
how to reproduce it if desktop.el is already handling these cases.