GNU bug report logs - #8310
update-game-score -r logic broken with MAX_SCORES

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 8310 in the body.
You can then email your comments to 8310 AT debbugs.gnu.org in the normal way.

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

Message #5 received at submit <at> debbugs.gnu.org (full text, mbox):

From: Paul Eggert <eggert <at> cs.ucla.edu>
To: bug-gnu-emacs <at> gnu.org
Subject: update-game-score -r logic broken with MAX_SCORES
Date: Mon, 21 Mar 2011 00:37:09 -0700

Here's a bug found by gcc -Wstrict-overflow (GCC 4.5.2) this one in
in update-game-score -r.  I plan to install the following patch.

update-game-score: fix bug with -r
* update-game-score.c (main): Don't set 'scores' to garbage when
-r is specified and scorecount != MAX_SCORES.  This bug was
introduced in the 2002-04-10 change, and was found with gcc
-Wstrict-overflow (GCC 4.5.2, x86-64).
=== modified file 'lib-src/update-game-score.c'
--- lib-src/update-game-score.c	2011-02-21 18:06:25 +0000
+++ lib-src/update-game-score.c	2011-03-21 07:17:22 +0000
@@ -242,13 +242,15 @@
   push_score (&scores, &scorecount, newscore, user_id, newdata);
   sort_scores (scores, scorecount, reverse);
   /* Limit the number of scores.  If we're using reverse sorting, then
-     we should increment the beginning of the array, to skip over the
-     *smallest* scores.  Otherwise, we just decrement the number of
-     scores, since the smallest will be at the end. */
+     also increment the beginning of the array, to skip over the
+     *smallest* scores.  Otherwise, just decrementing the number of
+     scores suffices, since the smallest is at the end. */
   if (scorecount > MAX_SCORES)
-    scorecount -= (scorecount - MAX_SCORES);
-  if (reverse)
-    scores += (scorecount - MAX_SCORES);
+    {
+      if (reverse)
+	scores += (scorecount - MAX_SCORES);
+      scorecount = MAX_SCORES;
+    }
   if (write_scores (scorefile, scores, scorecount) < 0)
     {
       unlock_file (scorefile, lockstate);

Message #10 received at 8310-done <at> debbugs.gnu.org (full text, mbox):

From: Paul Eggert <eggert <at> cs.ucla.edu>
To: 8310-done <at> debbugs.gnu.org, 8318-done <at> debbugs.gnu.org, 
	8306-done <at> debbugs.gnu.org, 8303-done <at> debbugs.gnu.org, 
	8277-done <at> debbugs.gnu.org, 8298-done <at> debbugs.gnu.org, 
	8290-done <at> debbugs.gnu.org, 8278-done <at> debbugs.gnu.org
Subject: fix merged to trunk
Date: Wed, 23 Mar 2011 15:06:46 -0700

I committed a fix to the trunk for this,
as part of a recent merge (bzr 103721).

Previous Next

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