bug#18623: 24.3; tramp: unhelpful error message when copy program is unavailable

[Michael Albinus]

Zack Weinberg <zackw@panix.com> writes:

> `Cannot find copy program: rsync' is a perfectly sensible error message;
> this bug would be resolved if _that_ were what showed up in the echo area.

I've committed the following patch to the Tramp repo as well as to the
Emacs repo (branch emacs-24):

--8<---------------cut here---------------start------------->8---
*** /tmp/ediff13503WDN  2014-12-21 12:15:48.715138335 +0100
--- /home/albinus/src/tramp/lisp/tramp.el       2014-12-21 11:30:14.424791817 
+0100
***************
*** 3086,3200 ****
    (setq filename (expand-file-name filename))
    (let (result local-copy remote-copy)
      (with-parsed-tramp-file-name filename nil
!       (with-tramp-progress-reporter
!         v 3 (format "Inserting `%s'" filename)
!       (unwind-protect
!           (if (not (file-exists-p filename))
!               (progn
!                 ;; We don't raise a Tramp error, because it might be
!                 ;; suppressed, like in `find-file-noselect-1'.
!                 (tramp-message
!                  v 1 "File not `%s' found on remote host" filename)
!                 (signal 'file-error
!                         (list "File not found on remote host" filename)))
! 
!             (if (and (tramp-local-host-p v)
!                      (let (file-name-handler-alist)
!                        (file-readable-p localname)))
!                 ;; Short track: if we are on the local host, we can
!                 ;; run directly.
!                 (setq result
!                       (tramp-run-real-handler
!                        'insert-file-contents
!                        (list localname visit beg end replace)))
! 
!               ;; When we shall insert only a part of the file, we
!               ;; copy this part.  This works only for the shell file
!               ;; name handlers.
!               (when (and (or beg end)
!                          (tramp-get-method-parameter
!                           (tramp-file-name-method v) 'tramp-login-program))
!                 (setq remote-copy (tramp-make-tramp-temp-file v))
!                 ;; This is defined in tramp-sh.el.  Let's assume
!                 ;; this is loaded already.
!                 (tramp-compat-funcall
!                  'tramp-send-command
!                  v
!                  (cond
!                   ((and beg end)
!                    (format "dd bs=1 skip=%d if=%s count=%d of=%s"
!                            beg (tramp-shell-quote-argument localname)
!                            (- end beg) remote-copy))
!                   (beg
!                    (format "dd bs=1 skip=%d if=%s of=%s"
!                            beg (tramp-shell-quote-argument localname)
!                            remote-copy))
!                   (end
!                    (format "dd bs=1 count=%d if=%s of=%s"
!                            end (tramp-shell-quote-argument localname)
!                            remote-copy))))
!                 (setq tramp-temp-buffer-file-name nil beg nil end nil))
! 
!               ;; `insert-file-contents-literally' takes care to
!               ;; avoid calling jka-compr.  By let-binding
!               ;; `inhibit-file-name-operation', we propagate that
!               ;; care to the `file-local-copy' operation.
!               (setq local-copy
!                     (let ((inhibit-file-name-operation
!                            (when (eq inhibit-file-name-operation
!                                      'insert-file-contents)
!                              'file-local-copy)))
!                       (cond
!                        ((stringp remote-copy)
!                         (file-local-copy
!                          (tramp-make-tramp-file-name
!                           method user host remote-copy)))
!                        ((stringp tramp-temp-buffer-file-name)
!                         (copy-file filename tramp-temp-buffer-file-name 'ok)
!                         tramp-temp-buffer-file-name)
!                        (t (file-local-copy filename)))))
! 
!               ;; When the file is not readable for the owner, it
!               ;; cannot be inserted, even if it is readable for the
!               ;; group or for everybody.
!               (set-file-modes
!                local-copy (tramp-compat-octal-to-decimal "0600"))
! 
!               (when (and (null remote-copy)
!                          (tramp-get-method-parameter
!                           method 'tramp-copy-keep-tmpfile))
!                 ;; We keep the local file for performance reasons,
!                 ;; useful for "rsync".
!                 (setq tramp-temp-buffer-file-name local-copy))
! 
!               ;; We must ensure that `file-coding-system-alist'
!               ;; matches `local-copy'.  We must also use `visit',
!               ;; otherwise there might be an error in the
!               ;; `revert-buffer' function under XEmacs.
!               (let ((file-coding-system-alist
!                      (tramp-find-file-name-coding-system-alist
!                       filename local-copy)))
!                 (setq result
!                       (insert-file-contents
!                        local-copy visit beg end replace)))))
! 
!         ;; Save exit.
!         (progn
!           (when visit
!             (setq buffer-file-name filename)
!             (setq buffer-read-only (not (file-writable-p filename)))
!             (set-visited-file-modtime)
!             (set-buffer-modified-p nil))
!           (when (and (stringp local-copy)
!                      (or remote-copy (null tramp-temp-buffer-file-name)))
!             (delete-file local-copy))
!           (when (stringp remote-copy)
!             (delete-file
!              (tramp-make-tramp-file-name method user host remote-copy)))))))
! 
!     ;; Result.
!     (list (expand-file-name filename)
!         (cadr result))))
  
  (defun tramp-handle-load (file &optional noerror nomessage nosuffix 
must-suffix)
    "Like `load' for Tramp files."
--- 3086,3202 ----
    (setq filename (expand-file-name filename))
    (let (result local-copy remote-copy)
      (with-parsed-tramp-file-name filename nil
!       (unwind-protect
!         (if (not (file-exists-p filename))
!             (tramp-message v 0 "(New file)")
! 
!           (with-tramp-progress-reporter
!               v 3 (format "Inserting `%s'" filename)
!             (condition-case err
!                 (if (and (tramp-local-host-p v)
!                          (let (file-name-handler-alist)
!                            (file-readable-p localname)))
!                     ;; Short track: if we are on the local host, we can
!                     ;; run directly.
!                     (setq result
!                           (tramp-run-real-handler
!                            'insert-file-contents
!                            (list localname visit beg end replace)))
! 
!                   ;; When we shall insert only a part of the file, we
!                   ;; copy this part.  This works only for the shell file
!                   ;; name handlers.
!                   (when (and (or beg end)
!                              (tramp-get-method-parameter
!                               (tramp-file-name-method v)
!                               'tramp-login-program))
!                     (setq remote-copy (tramp-make-tramp-temp-file v))
!                     ;; This is defined in tramp-sh.el.  Let's assume
!                     ;; this is loaded already.
!                     (tramp-compat-funcall
!                      'tramp-send-command
!                      v
!                      (cond
!                       ((and beg end)
!                        (format "dd bs=1 skip=%d if=%s count=%d of=%s"
!                                beg (tramp-shell-quote-argument localname)
!                                (- end beg) remote-copy))
!                       (beg
!                        (format "dd bs=1 skip=%d if=%s of=%s"
!                                beg (tramp-shell-quote-argument localname)
!                                remote-copy))
!                       (end
!                        (format "dd bs=1 count=%d if=%s of=%s"
!                                end (tramp-shell-quote-argument localname)
!                                remote-copy))))
!                     (setq tramp-temp-buffer-file-name nil beg nil end nil))
! 
!                   ;; `insert-file-contents-literally' takes care to
!                   ;; avoid calling jka-compr.  By let-binding
!                   ;; `inhibit-file-name-operation', we propagate that
!                   ;; care to the `file-local-copy' operation.
!                   (setq local-copy
!                         (let ((inhibit-file-name-operation
!                                (when (eq inhibit-file-name-operation
!                                          'insert-file-contents)
!                                  'file-local-copy)))
!                           (cond
!                            ((stringp remote-copy)
!                             (file-local-copy
!                              (tramp-make-tramp-file-name
!                               method user host remote-copy)))
!                            ((stringp tramp-temp-buffer-file-name)
!                             (copy-file
!                              filename tramp-temp-buffer-file-name 'ok)
!                             tramp-temp-buffer-file-name)
!                            (t (file-local-copy filename)))))
! 
!                   ;; When the file is not readable for the owner, it
!                   ;; cannot be inserted, even if it is readable for the
!                   ;; group or for everybody.
!                   (set-file-modes
!                    local-copy (tramp-compat-octal-to-decimal "0600"))
! 
!                   (when (and (null remote-copy)
!                              (tramp-get-method-parameter
!                               method 'tramp-copy-keep-tmpfile))
!                     ;; We keep the local file for performance reasons,
!                     ;; useful for "rsync".
!                     (setq tramp-temp-buffer-file-name local-copy))
! 
!                   ;; We must ensure that `file-coding-system-alist'
!                   ;; matches `local-copy'.  We must also use `visit',
!                   ;; otherwise there might be an error in the
!                   ;; `revert-buffer' function under XEmacs.
!                   (let ((file-coding-system-alist
!                          (tramp-find-file-name-coding-system-alist
!                           filename local-copy)))
!                     (setq result
!                           (insert-file-contents
!                            local-copy visit beg end replace))))
!               (error
!                (add-hook 'find-file-not-found-functions
!                          `(lambda () (signal ',(car err) ',(cdr err)))
!                          nil t)
!                (signal (car err) (cdr err))))))
! 
!       ;; Save exit.
!       (progn
!         (when visit
!           (setq buffer-file-name filename)
!           (setq buffer-read-only (not (file-writable-p filename)))
!           (set-visited-file-modtime)
!           (set-buffer-modified-p nil))
!         (when (and (stringp local-copy)
!                    (or remote-copy (null tramp-temp-buffer-file-name)))
!           (delete-file local-copy))
!         (when (stringp remote-copy)
!           (delete-file
!            (tramp-make-tramp-file-name method user host remote-copy)))))
! 
!       ;; Result.
!       (list (expand-file-name filename)
!           (cadr result)))))
  
  (defun tramp-handle-load (file &optional noerror nomessage nosuffix 
must-suffix)
    "Like `load' for Tramp files."
--8<---------------cut here---------------end--------------->8---

Could you, please, check whether it fits your needs?

Best regards, Michael.