Re: [PATCH] Really prevent quitting in sensitive contexts

[Michael Albinus <michael.albinus@gmx.de>]

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Daniel Colascione <dancol@dancol.org> writes:

>> Are there bug#NNN where these are discussed?
>
> No. The motiviation is Tramp inflooping after a quit because it uses
> with-local-quit inside tramp-accept-process-output, which causes
> tramp-wait-for-regexp to retry infinitely and quickly.
>
> I found *that* behavior trying to figure out why M-x compile over
> Tramp was hanging not only Emacs, but also the SSH connection more
> generally. I *think* it has something to do with compilation-filter
> calling file-truename, which invokes Tramp's handler, which wants to
> talk over the same SSH connection that's spewing compilation messages,
> deadlocking something somewhere.

Please write a bug report, it should be solved in Tramp.

with-local-quit is used in tramp-accept-process-output by
intention. There were reports that Tramp hung, and couldn't be quit ...

Would the appended patch help (completely untested)?

Best regards, Michael.


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diff --git a/lisp/tramp.el b/lisp/tramp.el
index 82ac693d..af2bc4b2 100644
--- a/lisp/tramp.el
+++ b/lisp/tramp.el
@@ -4227,18 +4227,20 @@ performed successfully.  Any other value means an error."
 (defun tramp-accept-process-output (proc &optional timeout)
   "Like `accept-process-output' for Tramp processes.
 This is needed in order to hide `last-coding-system-used', which is set
-for process communication also."
+for process communication also.
+If the user quits via `C-g', it is propagated up to `tramp-file-name-handler'."
   (with-current-buffer (process-buffer proc)
     (let ((inhibit-read-only t)
 	  last-coding-system-used
 	  result)
-      ;; JUST-THIS-ONE is set due to Bug#12145.
-      (tramp-message
-       proc 10 "%s %s %s %s\n%s"
-       proc timeout (process-status proc)
-       (with-local-quit
-	 (setq result (accept-process-output proc timeout nil t)))
-       (buffer-string))
+      ;; JUST-THIS-ONE is set due to Bug#12145.  `with-local-quit'
+      ;; returns t in order to report success.
+      (if (with-local-quit
+	    (setq result (accept-process-output proc timeout nil t)) t)
+	  (tramp-message
+	   proc 10 "%s %s %s %s\n%s"
+	   proc timeout (process-status proc) result (buffer-string))
+	(keyboard-quit))
       result)))

 (defun tramp-search-regexp (regexp)