Re: File cleared when remote disk is full

[Michael Albinus]

Qiang Li <address@hidden> writes:

> I was editing a remote file using scp protocol while the remote disk
> got full, and when I saved the file it silently became empty on the
> disk. I happened to notice this before I close Emacs, so I had the
> chance to write the buffer to another file. I think this behavior is
> dangerous and should be classified as a bug.

Thanks for the report. I've added some return code checking for
out-of-band copying. Note, that this does not work when your local
system is running MS Windows - I don't know hot to check a return code
in cmd.exe. Does anybody know?

Alternatively, you can already now set `file-precious-flag' to `t'.
Tramp performs additional checks, and would warn you in case the copy
operation does not succeed. Since these checks slow down Tramp, they are
not ebabled by default.

> p.s. I was using TRAMP coming with Emacs 24.2 (debian sid)

Here's the patch I have prepared for Tramp 2.2.7-pre. It shall apply for
Emacs 24.2 as well, modulo changed line numbers.

--8<---------------cut here---------------start------------->8---
*** ~/src/tramp/lisp/tramp-sh.el.~master~       2012-12-05 14:42:21.435686599 
+0100
--- ~/src/tramp/lisp/tramp-sh.el        2012-12-05 14:37:54.734907100 +0100
***************
*** 2379,2395 ****
                ;; last longer than 60 secs.
                (let ((p (let ((default-directory
                                 (tramp-compat-temporary-file-directory)))
!                          (apply 'start-process
                                  (tramp-get-connection-name v)
                                  (tramp-get-connection-buffer v)
                                  copy-program
!                                 (append copy-args (list source target))))))
                  (tramp-message
                   orig-vec 6 "%s"
                   (mapconcat 'identity (process-command p) " "))
                  (tramp-compat-set-process-query-on-exit-flag p nil)
                  (tramp-process-actions
!                  p v nil tramp-actions-copy-out-of-band)))

            ;; Reset the transfer process properties.
            (tramp-message orig-vec 6 "\n%s" (buffer-string))
--- 2379,2419 ----
                ;; last longer than 60 secs.
                (let ((p (let ((default-directory
                                 (tramp-compat-temporary-file-directory)))
!                          (apply 'start-process-shell-command
                                  (tramp-get-connection-name v)
                                  (tramp-get-connection-buffer v)
                                  copy-program
!                                 (append
!                                  copy-args
!                                  (list
!                                   (shell-quote-argument source)
!                                   (shell-quote-argument target))
!                                  (unless (memq system-type '(windows-nt))
!                                    '(";" "echo"
!                                      "tramp_exit_status" "$?")))))))
                  (tramp-message
                   orig-vec 6 "%s"
                   (mapconcat 'identity (process-command p) " "))
                  (tramp-compat-set-process-query-on-exit-flag p nil)
                  (tramp-process-actions
!                  p v nil tramp-actions-copy-out-of-band)
!
!                 ;; Check the return code.  This does not work under
!                 ;; MS Windows.
!                 (unless (memq system-type '(windows-nt))
!                   (goto-char (point-max))
!                   (unless
!                       (re-search-backward "tramp_exit_status [0-9]+" nil t)
!                     (tramp-error
!                      orig-vec 'file-error
!                      "Couldn't find exit status of `%s'" (process-command p)))
!                   (skip-chars-forward "^ ")
!                   (unless (zerop (read (current-buffer)))
!                     (forward-line -1)
!                     (tramp-error
!                      orig-vec 'file-error
!                      "Error copying: `%s'"
!                      (buffer-substring (point-min) (point-at-eol)))))))

            ;; Reset the transfer process properties.
            (tramp-message orig-vec 6 "\n%s" (buffer-string))
--8<---------------cut here---------------end--------------->8---

Best regards, Michael.