--- NoGnus/dns-mode.el	2009-01-22 08:09:02 +0000
+++ Emacs/dns-mode.el	2009-01-05 03:24:01 +0000
@@ -49,7 +49,7 @@
 
 (defgroup dns-mode nil
   "DNS master file mode configuration."
-  :group 'comm)
+  :group 'data)
 
 (defconst dns-mode-classes '("IN" "CS" "CH" "HS")
   "List of strings with known DNS classes.")
@@ -89,6 +89,18 @@
   :type 'sexp
   :group 'dns-mode)
 
+(defcustom dns-mode-soa-auto-increment-serial t
+  "Whether to increment the SOA serial number automatically.
+
+If this variable is t, the serial number is incremented upon each save of
+the file.  If it is `ask', Emacs asks for confirmation whether it should
+increment the serial upon saving.  If nil, serials must be incremented
+manually with \\[dns-mode-soa-increment-serial]."
+  :type '(choice (const :tag "Always" t)
+		 (const :tag "Ask" ask)
+		 (const :tag "Never" nil))
+  :group 'dns-mode)
+
 ;; Syntax table.
 
 (defvar dns-mode-syntax-table
@@ -134,8 +146,12 @@
   (unless (featurep 'xemacs)
     (set (make-local-variable 'font-lock-defaults)
 	 '(dns-mode-font-lock-keywords nil nil ((?_ . "w")))))
+  (add-hook 'before-save-hook 'dns-mode-soa-maybe-increment-serial
+	    nil t)
   (easy-menu-add dns-mode-menu dns-mode-map))
 
+;;;###autoload (defalias 'zone-mode 'dns-mode)
+
 ;; Tools.
 
 ;;;###autoload
@@ -191,6 +207,21 @@
 	      (message "Replaced old serial %s with %s" serial new))
 	  (error "Cannot locate serial number in SOA record"))))))
 
+(defun dns-mode-soa-maybe-increment-serial ()
+  "Increment SOA serial if needed.
+
+This function is run from `before-save-hook'."
+  (when (and (buffer-modified-p)
+	     dns-mode-soa-auto-increment-serial
+	     (or (eq dns-mode-soa-auto-increment-serial t)
+		 (y-or-n-p "Increment SOA serial? ")))
+    ;; If `dns-mode-soa-increment-serial' signals an error saving will
+    ;; fail but that probably means that the serial should be fixed to
+    ;; comply with the RFC anyway! -rfr
+    (progn (dns-mode-soa-increment-serial)
+	   ;; We return nil in case this is used in write-contents-functions.
+	   nil)))
+
 ;;;###autoload(add-to-list 'auto-mode-alist '("\\.soa\\'" . dns-mode))
 
 (provide 'dns-mode)