GNU bug report logs - #5225
dired-diff should be more safe

Previous Next

To add a comment to this bug, you must first unarchive it, by sending
a message to control AT debbugs.gnu.org, with unarchive 5225 in the body.
You can then email your comments to 5225 AT debbugs.gnu.org in the normal way.

Toggle the display of automated, internal messages from the tracker.

Message #5 received at submit <at> emacsbugs.donarmstrong.com (full text, mbox):

From: Juri Linkov <juri <at> jurta.org>
To: emacs-pretest-bug <at> gnu.org
Subject: dired-diff should be more safe
Date: Wed, 16 Dec 2009 11:19:09 +0200

Currently using `dired-diff' has a high risk of deleting a file.

When two compared file names refer to the same file, or when one of them
is the directory name of the second file (thus the file is compared
against itself), then the user may not notice that `diff' compares the
same file with itself, and when `diff' says there are no differences,
decide to delete the file (thinking that two files have the same content).

The patch below eliminates this risk by signalling an error when
comparing the same file to itself:

=== modified file 'lisp/dired-aux.el'
--- lisp/dired-aux.el	2009-11-25 17:15:19 +0000
+++ lisp/dired-aux.el	2009-12-16 09:16:34 +0000
@@ -60,27 +60,44 @@
 		       (if (stringp diff-switches)
 			   diff-switches
 			 (mapconcat 'identity diff-switches " ")))))))
-  (diff file (dired-get-filename t) switches))
+  (let ((current (dired-get-filename t)))
+    (when (or (equal (expand-file-name file)
+		     (expand-file-name current))
+	      (and (file-directory-p file)
+		   (equal (expand-file-name current file)
+			  (expand-file-name current))))
+      (error "Attempt to compare the file to itself"))
+    (diff file current switches)))
 
 ;;;###autoload
 (defun dired-backup-diff (&optional switches)

-- 
Juri Linkov
http://www.jurta.org/emacs/

Message #10 received at 5225-done <at> debbugs.gnu.org (full text, mbox):

From: Juri Linkov <juri <at> jurta.org>
To: 5225-done <at> debbugs.gnu.org
Subject: Re: bug#5225: dired-diff should be more safe
Date: Thu, 17 Dec 2009 03:19:27 +0200

Fixed.

-- 
Juri Linkov
http://www.jurta.org/emacs/

Previous Next

GNU bug tracking system
Copyright (C) 1999 Darren O. Benham, 1997,2003 nCipher Corporation Ltd, 1994-97 Ian Jackson.