Re: TRAMP VC optimization: also breaks process filters -_-

[Michael Albinus]

Stefan Monnier <address@hidden> writes:

Hi,

>> I'm sad to report that blocking timers in TRAMP is not sufficient to avoid
>> it breaking other operations: process filters can also run while TRAMP is
>> sending, and waiting for the result of, a command.
>
> I'm not sure what is the problem with timers and/or process filters
> (e.g. I don't see any process filters in your backtrace), so maybe I'm
> misunderstanding the problem, but FWIW, here's what I noticed:
>
>>   tramp-user-error(nil "Not a Tramp file name: \"%s\"" 
>> "/Users/slippycheeze/.emacs.d/network-security.data")
>>   
>> tramp-dissect-file-name("/Users/slippycheeze/.emacs.d/network-security.data")
>>   tramp-vc-file-name-handler(expand-file-name 
>> "/Users/slippycheeze/.emacs.d/network-security.data" 
>> "/gssh:slippycheeze.X.XXXXXXXX.XXX:")
>
> This indicates that Tramp gets confused and thinks that the
> tramp-vc-file-name-handler was called in response to expand-file-name on
> the file "/Users/slippycheeze/.emacs.d/network-security.data" whereas
> it's called because of the directory argument.
>
> So I believe the (untested) patch below should fix the immediate problem.
> Can you confirm?
>
> Michael?

Yes, the analysis is correct. However, we don't need to check this for
every Tramp invocation. Daniel's reports have been covered always
vc-registered. And indeed, the related `tramp-vc-file-name-handler'
seems to expect always a Tramp file name, which is not true for filters
and sentinels which run for non-Tramp processes.

Daniel, does the appended patch fixes the issue for you?

>         Stefan

Best regards, Michael.

*** /tmp/ediffKys9Ze    2019-05-07 17:22:48.298108293 +0200
--- /home/albinus/src/tramp/lisp/tramp-sh.el    2019-05-07 17:19:08.563550390 
+0200
***************
*** 3550,3573 ****
           (tramp-replace-environment-variables
            (apply #'tramp-file-name-for-operation operation args)))
          (fn (assoc operation tramp-sh-file-name-handler-alist)))
!       (with-parsed-tramp-file-name filename nil
!       (cond
!        ;; That's what we want: file names, for which checks are
!        ;; applied.  We assume that VC uses only `file-exists-p' and
!        ;; `file-readable-p' checks; otherwise we must extend the
!        ;; list.  We do not perform any action, but return nil, in
!        ;; order to keep `vc-registered' running.
!        ((and fn (memq operation '(file-exists-p file-readable-p)))
!         (add-to-list 'tramp-vc-registered-file-names localname 'append)
!         nil)
!        ;; `process-file' and `start-file-process' shall be ignored.
!        ((and fn (eq operation 'process-file) 0))
!        ((and fn (eq operation 'start-file-process) nil))
!        ;; Tramp file name handlers like `expand-file-name'.  They
!        ;; must still work.
!        (fn (save-match-data (apply (cdr fn) args)))
!        ;; Default file name handlers, we don't care.
!        (t (tramp-run-real-handler operation args)))))))

  (defun tramp-sh-handle-file-notify-add-watch (file-name flags _callback)
    "Like `file-notify-add-watch' for Tramp files."
--- 3550,3579 ----
           (tramp-replace-environment-variables
            (apply #'tramp-file-name-for-operation operation args)))
          (fn (assoc operation tramp-sh-file-name-handler-alist)))
!       ;; If connection is not established yet, or if it is not a Tramp
!       ;; file, run the real handler.  This can happen if timers,
!       ;; process filters, or process sentinels not related to us are
!       ;; activated.
!       (if (not (tramp-connectable-p filename))
!         (tramp-run-real-handler operation args)
!       (with-parsed-tramp-file-name filename nil
!         (cond
!          ;; That's what we want: file names, for which checks are
!          ;; applied.  We assume that VC uses only `file-exists-p' and
!          ;; `file-readable-p' checks; otherwise we must extend the
!          ;; list.  We do not perform any action, but return nil, in
!          ;; order to keep `vc-registered' running.
!          ((and fn (memq operation '(file-exists-p file-readable-p)))
!           (add-to-list 'tramp-vc-registered-file-names localname 'append)
!           nil)
!          ;; `process-file' and `start-file-process' shall be ignored.
!          ((and fn (eq operation 'process-file) 0))
!          ((and fn (eq operation 'start-file-process) nil))
!          ;; Tramp file name handlers like `expand-file-name'.  They
!          ;; must still work.
!          (fn (save-match-data (apply (cdr fn) args)))
!          ;; Default file name handlers, we don't care.
!          (t (tramp-run-real-handler operation args))))))))

  (defun tramp-sh-handle-file-notify-add-watch (file-name flags _callback)
    "Like `file-notify-add-watch' for Tramp files."