* lisp/desktop.el (desktop-auto-save-enable)

(desktop-auto-save-disable): New functions.
(desktop-save-mode, desktop-auto-save-timeout): Use them.
(desktop-read): Disable the autosave before loading the desktop,
and enable afterwards.

Fixes: debbugs:17351

2 files changed, 26 insertions, 8 deletions

diff --git a/lisp/ChangeLog b/lisp/ChangeLog
index da8d49ae0a9..5981c50af77 100644
--- a/lisp/ChangeLog
+++ b/lisp/ChangeLog
@@ -1,3 +1,11 @@
+2014-06-24  Juri Linkov  <juri@jurta.org>
+
+        * desktop.el (desktop-auto-save-enable)
+        (desktop-auto-save-disable): New functions.
+        (desktop-save-mode, desktop-auto-save-timeout): Use them.
+        (desktop-read): Disable the autosave before loading the desktop,
+        and enable afterwards.  (Bug#17351)
+
 2014-06-24  Stefan Monnier  <monnier@iro.umontreal.ca>
 
         Fix some indentation problem with \; and pipes (bug#17842).
diff --git a/lisp/desktop.el b/lisp/desktop.el
index d420a6416a9..26d288bf9cd 100644
--- a/lisp/desktop.el
+++ b/lisp/desktop.el
@@ -174,11 +174,8 @@ For further details, see info node `(emacs)Saving Emacs Sessions'."
   :global t
   :group 'desktop
   (if desktop-save-mode
-      (when (and (integerp desktop-auto-save-timeout)
-                 (> desktop-auto-save-timeout 0))
-        (add-hook 'window-configuration-change-hook 'desktop-auto-save-set-timer))
-    (remove-hook 'window-configuration-change-hook 'desktop-auto-save-set-timer)
-    (desktop-auto-save-cancel-timer)))
+      (desktop-auto-save-enable)
+    (desktop-auto-save-disable)))
 
 (defun desktop-save-mode-off ()
   "Disable `desktop-save-mode'.  Provided for use in hooks."
@@ -219,9 +216,8 @@ Zero or nil means disable auto-saving due to idleness."
          (set-default symbol value)
          (ignore-errors
            (if (and (integerp value) (> value 0))
-               (add-hook 'window-configuration-change-hook 'desktop-auto-save-set-timer)
-             (remove-hook 'window-configuration-change-hook 'desktop-auto-save-set-timer)
-             (desktop-auto-save-cancel-timer))))
+               (desktop-auto-save-enable value)
+             (desktop-auto-save-disable))))
   :group 'desktop
   :version "24.4")
 
@@ -1132,6 +1128,10 @@ Using it may cause conflicts.  Use it anyway? " owner)))))
                 (unless desktop-dirname
                   (message "Desktop file in use; not loaded.")))
             (desktop-lazy-abort)
+            ;; Temporarily disable the autosave that will leave it
+            ;; disabled when loading the desktop fails with errors,
+            ;; thus not overwriting the desktop with broken contents.
+            (desktop-auto-save-disable)
             ;; Evaluate desktop buffer and remember when it was modified.
             (load (desktop-full-file-name) t t t)
             (setq desktop-file-modtime (nth 5 (file-attributes (desktop-full-file-name))))
@@ -1184,6 +1184,7 @@ Using it may cause conflicts.  Use it anyway? " owner)))))
                                   (set-window-prev-buffers window nil)
                                   (set-window-next-buffers window nil))))
             (setq desktop-saved-frameset nil)
+            (desktop-auto-save-enable)
             t))
       ;; No desktop file found.
       (desktop-clear)
@@ -1230,6 +1231,15 @@ directory DIRNAME."
 ;; Auto-Saving.
 (defvar desktop-auto-save-timer nil)
 
+(defun desktop-auto-save-enable (&optional timeout)
+  (when (and (integerp (or timeout desktop-auto-save-timeout))
+             (> (or timeout desktop-auto-save-timeout) 0))
+    (add-hook 'window-configuration-change-hook 'desktop-auto-save-set-timer)))
+
+(defun desktop-auto-save-disable ()
+  (remove-hook 'window-configuration-change-hook 'desktop-auto-save-set-timer)
+  (desktop-auto-save-cancel-timer))
+
 (defun desktop-auto-save ()
   "Save the desktop periodically.
 Called by the timer created in `desktop-auto-save-set-timer'."