Optionally check the newsrc.eld file's timestamp before saving it.

[gnus] / lisp / gnus-start.el

diff --git a/lisp/gnus-start.el b/lisp/gnus-start.el
index 9f3f469..5b734d0 100644 (file)
--- a/lisp/gnus-start.el
+++ b/lisp/gnus-start.el
@@ -1,6 +1,6 @@
 ;;; gnus-start.el --- startup functions for Gnus
 
-;; Copyright (C) 1996-2013 Free Software Foundation, Inc.
+;; Copyright (C) 1996-2014 Free Software Foundation, Inc.
 
 ;; Author: Lars Magne Ingebrigtsen <larsi@gnus.org>
 ;; Keywords: news
@@ -30,6 +30,7 @@
 (require 'gnus-spec)
 (require 'gnus-range)
 (require 'gnus-util)
+(require 'gnus-cloud)
 (autoload 'message-make-date "message")
 (autoload 'gnus-agent-read-servers-validate "gnus-agent")
 (autoload 'gnus-agent-save-local "gnus-agent")
@@ -441,6 +442,14 @@ See also `gnus-before-startup-hook'."
   :group 'gnus-newsrc
   :type 'hook)
 
+(defcustom gnus-save-newsrc-file-check-timestamp nil
+  "Check the modification time of the newsrc.eld file before saving it.
+When the newsrc.eld file is updated by multiple machines,
+checking the file's modification time is a good way to avoid
+overwriting updated data."
+  :group 'gnus-newsrc
+  :type 'boolean)
+
 (defcustom gnus-save-newsrc-hook nil
   "A hook called before saving any of the newsrc files."
   :group 'gnus-newsrc
@@ -888,6 +897,11 @@ If REGEXP is given, lines that match it will be deleted."
       (setq buffer-save-without-query t)
       (erase-buffer)
       (setq buffer-file-name dribble-file)
+      ;; The buffer may be shrunk a lot when deleting old entries.
+      ;; It caused the auto-saving to stop.
+      (if (featurep 'emacs)
+         (set (make-local-variable 'auto-save-include-big-deletions) t)
+       (set (make-local-variable 'disable-auto-save-when-buffer-shrinks) nil))
       (auto-save-mode t)
       (buffer-disable-undo)
       (bury-buffer (current-buffer))
@@ -2777,6 +2791,7 @@ If FORCE is non-nil, the .newsrc file is read."
       'msdos-long-file-names
       (lambda () t))))
 
+(defvar gnus-save-newsrc-file-last-timestamp nil)
 (defun gnus-save-newsrc-file (&optional force)
   "Save .newsrc file."
   ;; Note: We cannot save .newsrc file if all newsgroups are removed
@@ -2815,12 +2830,30 @@ If FORCE is non-nil, the .newsrc file is read."
          (erase-buffer)
           (gnus-message 5 "Saving %s.eld..." gnus-current-startup-file)
 
+          ;; check timestamp of `gnus-current-startup-file'.eld against
+          ;; `gnus-save-newsrc-file-last-timestamp'
+          (when gnus-save-newsrc-file-check-timestamp
+            (let* ((checkfile (concat gnus-current-startup-file ".eld"))
+                   (mtime (nth 5 (file-attributes checkfile))))
+              (when (and gnus-save-newsrc-file-last-timestamp
+                         (time-less-p gnus-save-newsrc-file-last-timestamp
+                                      mtime))
+                (unless (y-or-n-p
+                         (format "%s was updated externally after %s, save?"
+                                 checkfile
+                                 (format-time-string
+                                  "%c"
+                                  gnus-save-newsrc-file-last-timestamp)))
+                (error "Couldn't save %s: updated externally" checkfile)))))
+
           (if gnus-save-startup-file-via-temp-buffer
               (let ((coding-system-for-write gnus-ding-file-coding-system)
                     (standard-output (current-buffer)))
                 (gnus-gnus-to-quick-newsrc-format)
                 (gnus-run-hooks 'gnus-save-quick-newsrc-hook)
-                (save-buffer))
+                (save-buffer)
+                (setq gnus-save-newsrc-file-last-timestamp
+                            (nth 5 (file-attributes buffer-file-name))))
             (let ((coding-system-for-write gnus-ding-file-coding-system)
                   (version-control gnus-backup-startup-file)
                   (startup-file (concat gnus-current-startup-file ".eld"))
@@ -2855,7 +2888,9 @@ If FORCE is non-nil, the .newsrc file is read."
 
                       ;; Replace the existing startup file with the temp file.
                       (rename-file working-file startup-file t)
-                      (gnus-set-file-modes startup-file setmodes)))
+                      (gnus-set-file-modes startup-file setmodes)
+                      (setq gnus-save-newsrc-file-last-timestamp
+                            (nth 5 (file-attributes startup-file)))))
                 (condition-case nil
                     (delete-file working-file)
                   (file-error nil)))))