Fix comparisons of file ownership on MS-Windows for the Administrator user.

 lisp/files.el (file-ownership-preserved-p): Pass `integer' as an
 explicit 2nd argument to `file-attributes'.  If the file's owner
 is the Administrators group on Windows, and the current user is
 Administrator, consider that a match.
 lisp/server.el (server-ensure-safe-dir): Consider server directory
 safe on MS-Windows if its owner is the Administrators group while
 the current Emacs user is Administrator.  Use `=' to compare
 numerical UIDs, since they could be integers or floats.

3 files changed, 27 insertions, 3 deletions

diff --git a/lisp/ChangeLog b/lisp/ChangeLog
index 1b8a7641b35..6685e355360 100644
--- a/lisp/ChangeLog
+++ b/lisp/ChangeLog
@@ -1,3 +1,15 @@
+2011-03-11  Eli Zaretskii  <eliz@gnu.org>
+
+        * files.el (file-ownership-preserved-p): Pass `integer' as an
+        explicit 2nd argument to `file-attributes'.  If the file's owner
+        is the Administrators group on Windows, and the current user is
+        Administrator, consider that a match.
+
+        * server.el (server-ensure-safe-dir): Consider server directory
+        safe on MS-Windows if its owner is the Administrators group while
+        the current Emacs user is Administrator.  Use `=' to compare
+        numerical UIDs, since they could be integers or floats.
+
 2011-03-07  Chong Yidong  <cyd@stupidchicken.com>
 
         * Version 23.3 released.
diff --git a/lisp/files.el b/lisp/files.el
index 88063aed2b9..91fed0d1274 100644
--- a/lisp/files.el
+++ b/lisp/files.el
@@ -3752,11 +3752,17 @@ we do not remove backup version numbers, only true file version numbers."
   (let ((handler (find-file-name-handler file 'file-ownership-preserved-p)))
     (if handler
         (funcall handler 'file-ownership-preserved-p file)
-      (let ((attributes (file-attributes file)))
+      (let ((attributes (file-attributes file 'integer)))
         ;; Return t if the file doesn't exist, since it's true that no
         ;; information would be lost by an (attempted) delete and create.
         (or (null attributes)
-            (= (nth 2 attributes) (user-uid)))))))
+            (= (nth 2 attributes) (user-uid))
+            ;; Files created on Windows by Administrator (RID=500)
+            ;; have the Administrators group (RID=544) recorded as
+            ;; their owner.  Rewriting them will still preserve the
+            ;; owner.
+            (and (eq system-type 'windows-nt)
+                 (= (user-uid) 500) (= (nth 2 attributes) 544)))))))
 
 (defun file-name-sans-extension (filename)
   "Return FILENAME sans final \"extension\".
diff --git a/lisp/server.el b/lisp/server.el
index f62a7c73abc..816a072bf75 100644
--- a/lisp/server.el
+++ b/lisp/server.el
@@ -474,7 +474,13 @@ See variable `server-auth-dir' for details."
                               (file-name-as-directory dir))
                       :warning)
                      (throw :safe t))
-                   (unless (eql uid (user-uid)) ; is the dir ours?
+                   (unless (or (= uid (user-uid)) ; is the dir ours?
+                               (and w32
+                                    ;; Files created on Windows by
+                                    ;; Administrator (RID=500) have
+                                    ;; the Administrators (RID=544)
+                                    ;; group recorded as the owner.
+                                    (= uid 544) (= (user-uid) 500)))
                      (throw :safe nil))
                    (when w32                    ; on NTFS?
                      (throw :safe t))