From mboxrd@z Thu Jan 1 00:00:00 1970 From: "Shawn O. Pearce" Subject: [JGIT PATCH 01/11] Fix more computation of integer average overflows Date: Wed, 29 Apr 2009 11:54:38 -0700 Message-ID: <1241031288-23437-2-git-send-email-spearce@spearce.org> References: <1241031288-23437-1-git-send-email-spearce@spearce.org> Cc: git@vger.kernel.org To: Robin Rosenberg X-From: git-owner@vger.kernel.org Wed Apr 29 20:55:56 2009 Return-path: Envelope-to: gcvg-git-2@gmane.org Received: from vger.kernel.org ([209.132.176.167]) by lo.gmane.org with esmtp (Exim 4.50) id 1LzEwk-0003Rz-WB for gcvg-git-2@gmane.org; Wed, 29 Apr 2009 20:55:55 +0200 Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1756348AbZD2Syx (ORCPT ); Wed, 29 Apr 2009 14:54:53 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1753748AbZD2Syv (ORCPT ); Wed, 29 Apr 2009 14:54:51 -0400 Received: from george.spearce.org ([209.20.77.23]:32870 "EHLO george.spearce.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754386AbZD2Syu (ORCPT ); Wed, 29 Apr 2009 14:54:50 -0400 Received: by george.spearce.org (Postfix, from userid 1000) id 3544A3806E; Wed, 29 Apr 2009 18:54:50 +0000 (UTC) X-Spam-Checker-Version: SpamAssassin 3.2.4 (2008-01-01) on george.spearce.org X-Spam-Level: X-Spam-Status: No, score=-4.4 required=4.0 tests=ALL_TRUSTED,BAYES_00 autolearn=ham version=3.2.4 Received: from localhost.localdomain (localhost [127.0.0.1]) by george.spearce.org (Postfix) with ESMTP id 755F938064; Wed, 29 Apr 2009 18:54:49 +0000 (UTC) X-Mailer: git-send-email 1.6.3.rc3.199.g24398 In-Reply-To: <1241031288-23437-1-git-send-email-spearce@spearce.org> Sender: git-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: git@vger.kernel.org Archived-At: In 1d99aaab8e364c6ad722437e43c77fd54e13b071 Matthias Sohn pointed out that (low+high)/2 can overflow, so (low+high)>>>1 is a better choice when the result will be used as an array index. Signed-off-by: Shawn O. Pearce --- Unchanged. .../src/org/spearce/jgit/lib/PackIndexV1.java | 2 +- .../src/org/spearce/jgit/lib/PackIndexV2.java | 6 +++--- 2 files changed, 4 insertions(+), 4 deletions(-) diff --git a/org.spearce.jgit/src/org/spearce/jgit/lib/PackIndexV1.java b/org.spearce.jgit/src/org/spearce/jgit/lib/PackIndexV1.java index fdaa094..0ad29e1 100644 --- a/org.spearce.jgit/src/org/spearce/jgit/lib/PackIndexV1.java +++ b/org.spearce.jgit/src/org/spearce/jgit/lib/PackIndexV1.java @@ -129,7 +129,7 @@ long findOffset(final AnyObjectId objId) { int high = data.length / (4 + Constants.OBJECT_ID_LENGTH); int low = 0; do { - final int mid = (low + high) / 2; + final int mid = (low + high) >>> 1; final int pos = ((4 + Constants.OBJECT_ID_LENGTH) * mid) + 4; final int cmp = objId.compareTo(data, pos); if (cmp < 0) diff --git a/org.spearce.jgit/src/org/spearce/jgit/lib/PackIndexV2.java b/org.spearce.jgit/src/org/spearce/jgit/lib/PackIndexV2.java index eb56ed9..b539547 100644 --- a/org.spearce.jgit/src/org/spearce/jgit/lib/PackIndexV2.java +++ b/org.spearce.jgit/src/org/spearce/jgit/lib/PackIndexV2.java @@ -108,7 +108,7 @@ PackIndexV2(final InputStream fd) throws IOException { final int intNameLen = (int) nameLen; final byte[] raw = new byte[intNameLen]; - final int[] bin = new int[intNameLen >> 2]; + final int[] bin = new int[intNameLen >>> 2]; NB.readFully(fd, raw, 0, raw.length); for (int i = 0; i < bin.length; i++) bin[i] = NB.decodeInt32(raw, i << 2); @@ -212,12 +212,12 @@ boolean hasCRC32Support() { private int binarySearchLevelTwo(final AnyObjectId objId, final int levelOne) { final int[] data = names[levelOne]; - int high = offset32[levelOne].length >> 2; + int high = offset32[levelOne].length >>> 2; if (high == 0) return -1; int low = 0; do { - final int mid = (low + high) >> 1; + final int mid = (low + high) >>> 1; final int mid4 = mid << 2; final int cmp; -- 1.6.3.rc3.199.g24398