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From: "Shawn O. Pearce" <spearce@spearce.org>
To: "Sohn, Matthias" <matthias.sohn@sap.com>
Cc: Robin Rosenberg <robin.rosenberg@dewire.com>, git@vger.kernel.org
Subject: Re: [PATCH JGIT] Computation of average could overflow
Date: Mon, 27 Apr 2009 16:17:57 -0700	[thread overview]
Message-ID: <20090427231757.GM23604@spearce.org> (raw)
In-Reply-To: <366BBB1215D0AB4B8A153AF047A2878002FCE7E7@dewdfe18.wdf.sap.corp>

"Sohn, Matthias" <matthias.sohn@sap.com> wrote:
> The code computes the average of two integers using either division or
> signed right shift, and then uses the result as the
> index of an array. If the values being averaged are very large, this can
> overflow (resulting in the computation of a negative
> average). Assuming that the result is intended to be nonnegative, you
> can use an unsigned right shift instead. In other
> words, rather that using (low+high)/2, use (low+high) >>> 1

Thanks, applied.  But your patch was line wrapped.  I had to unwrap
it by hand.  Please try to configure your MUA not to line wrap
patches when it sends them.  :-|
 
>  .../src/org/spearce/jgit/dircache/DirCache.java    |    2 +-
>  .../src/org/spearce/jgit/lib/Tree.java             |    2 +-
>  2 files changed, 2 insertions(+), 2 deletions(-)

-- 
Shawn.

      parent reply	other threads:[~2009-04-27 23:18 UTC|newest]

Thread overview: 9+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2009-04-27 23:02 [PATCH JGIT] Computation of average could overflow Sohn, Matthias
2009-04-27 23:05 ` [PATCH JGIT] Method invokes inefficient new String(String) constructor Sohn, Matthias
2009-04-27 23:08   ` [PATCH JGIT] Method invokes inefficient Number constructor; use static valueOf instead Sohn, Matthias
2009-04-27 23:10     ` [PATCH JGIT] Method ignores results of InputStream.skip() Sohn, Matthias
2009-04-27 23:21       ` Shawn O. Pearce
2009-04-28 22:26       ` Sohn, Matthias
2009-04-27 23:15     ` [PATCH JGIT] Method invokes inefficient Number constructor; use static valueOf instead Shawn O. Pearce
2009-04-27 23:17   ` [PATCH JGIT] Method invokes inefficient new String(String) constructor Shawn O. Pearce
2009-04-27 23:17 ` Shawn O. Pearce [this message]

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