* net/tramp.el (tramp-default-method): Before setting to "pscp",

check whether package password.el is loaded, or Pageant is running.

1 files changed, 27 insertions, 4 deletions

diff --git a/lisp/net/tramp.el b/lisp/net/tramp.el
index a45e1a22ad..b2e4ec814f 100644
--- a/lisp/net/tramp.el
+++ b/lisp/net/tramp.el
@@ -684,10 +684,33 @@ various functions for details."
   :type '(repeat (list string function string)))
 
 (defcustom tramp-default-method
-  (if (and (fboundp 'executable-find)
-	   (executable-find "pscp"))
-      "pscp"
-    "scp")
+  (or
+   ;; An external copy method seems to be preferred, because it is
+   ;; much more performant for large files, and it hasn't too serious
+   ;; delays for small files.  But it must be ensured that there
+   ;; aren't permanent password queries.  Either the copy method shall
+   ;; reuse other channels (ControlMaster of OpenSSH does it), a
+   ;; password agent like "ssh-agent" or "Pageant" shall run, or the
+   ;; optional password.el package shall be active for password caching.
+   (and (fboundp 'executable-find)
+	;; Check whether PuTTY is installed.
+	(executable-find "pscp")
+	(if (or
+	     ;; password.el is loaded.
+	     (fboundp 'password-read)
+	     ;; Pageant is running.
+	     (and (fboundp 'w32-window-exists-p)
+		  (funcall (symbol-function 'w32-window-exists-p)
+			   "Pageant" "Pageant")))
+	    ;; We know that the password will not be retrieved again.
+	    "pscp"
+	  ;; When "pscp" exists, there is also "plink".
+	  "plink"))
+   ;; Under UNIX, ControlMaster is activated.  This does not work
+   ;; under Cygwin, but ssh-agent must be enabled then anyway due to
+   ;; the pseudo-tty problem of Cygwin's OpenSSH implementation.  So
+   ;; it doesn't hurt to use "scp".
+   "scp")
   "*Default method to use for transferring files.
 See `tramp-methods' for possibilities.
 Also see `tramp-default-method-alist'."