From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 17B10ECAAA3 for ; Fri, 26 Aug 2022 15:53:55 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1343602AbiHZPxy (ORCPT ); Fri, 26 Aug 2022 11:53:54 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:40734 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S237300AbiHZPxw (ORCPT ); Fri, 26 Aug 2022 11:53:52 -0400 Received: from out5-smtp.messagingengine.com (out5-smtp.messagingengine.com [66.111.4.29]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 93BA0220D0 for ; Fri, 26 Aug 2022 08:53:51 -0700 (PDT) Received: from compute3.internal (compute3.nyi.internal [10.202.2.43]) by mailout.nyi.internal (Postfix) with ESMTP id 258FC5C02CE; Fri, 26 Aug 2022 11:53:49 -0400 (EDT) Received: from imap46 ([10.202.2.96]) by compute3.internal (MEProxy); Fri, 26 Aug 2022 11:53:49 -0400 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=hurrell.net; h= cc:cc:content-type:date:date:from:from:in-reply-to:in-reply-to :message-id:mime-version:references:reply-to:sender:subject :subject:to:to; s=fm2; t=1661529229; x=1661615629; bh=EQswOZSY31 7d3psFSt3SVgJbkSqTgFymg1nKfobPFoY=; b=WHM8rvD8qHx1F0L9UWtNJINj1I SmjzgSRy5FIhA/2z6ledS85Yb/+alf94n1I2hpDeQizaFcuilZgt38PBIHeIVPgd k38Oextdh4feIJbSozSVKzoYtwg+k4m+DvxVY6/mHhWpj1Mr2W1jcrDAeNm3SQ5w hT96hZyV/3A7HSxs1djNfh6+o42aDSwVNJcMQKmaewrFzycIBZrAthijjuixPXiO eFhDIY3BhhqiAnwD9SM2gB9DpEIXiEG64nBC3eW1MuzWECg8X7DY4enYNrIhGSUa V69b3wqvM1QDSxP5flwAlF6WfMM5pESE3aJMBJq2DhMrouC1OUM2Ak9oaZ5w== DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d= messagingengine.com; h=cc:cc:content-type:date:date:feedback-id :feedback-id:from:from:in-reply-to:in-reply-to:message-id :mime-version:references:reply-to:sender:subject:subject:to:to :x-me-proxy:x-me-proxy:x-me-sender:x-me-sender:x-sasl-enc; s= fm1; t=1661529229; x=1661615629; bh=EQswOZSY317d3psFSt3SVgJbkSqT gFymg1nKfobPFoY=; b=FIWpFQavEj9d/ajzUXg3Wo9BWCXJL4frfC1SqOD+G1sE Tag9C+E8XeaeQFO17dXU9a17iQeUcC9WitkL+JbjAHddFHhzAueN5ao/cruc3pYi 8pK1J+K8eqmj2y8a5w7MXqaN6JMj4nLn+zTiR9p2MDLlBw7uAHsnWmXxsLG77Jr0 clWUoobkJlJI7Dn/ifBm1ATaeG74rzX9qFcxHGE34ZB9uwNZGSXMdbxugp5MBHtQ FpDJ4jIdRwNzOLvguP3F45Xy7TIvJqcx5HGtu5xZPiNc8M4BMLycuhHwDHucq5ta X6MLQPDbGb5Itqg3sZ/PL15Cg3NoPh4zNPshx7GpWw== X-ME-Sender: X-ME-Proxy-Cause: gggruggvucftvghtrhhoucdtuddrgedvfedrvdejhedgleefucetufdoteggodetrfdotf fvucfrrhhofhhilhgvmecuhfgrshhtofgrihhlpdfqfgfvpdfurfetoffkrfgpnffqhgen uceurghilhhouhhtmecufedttdenucesvcftvggtihhpihgvnhhtshculddquddttddmne goufhushhpvggtthffohhmrghinhculdegledmnecujfgurhepofgfggfkjghffffhvfev ufgtsehttdertderredtnecuhfhrohhmpedfifhrvghgucfjuhhrrhgvlhhlfdcuoehgrh gvgheshhhurhhrvghllhdrnhgvtheqnecuggftrfgrthhtvghrnhepteduvddtffeltddt feekfedugedtjeeufeevjeefhfetteegtdeludfhieeugfffnecuffhomhgrihhnpehgih htrdhiohdpphhusghlihgtqdhinhgsohigrdhorhhgnecuvehluhhsthgvrhfuihiivgep tdenucfrrghrrghmpehmrghilhhfrhhomhepghhrvghgsehhuhhrrhgvlhhlrdhnvght X-ME-Proxy: Feedback-ID: i12114735:Fastmail Received: by mailuser.nyi.internal (Postfix, from userid 501) id 742B82A20075; Fri, 26 Aug 2022 11:53:48 -0400 (EDT) X-Mailer: MessagingEngine.com Webmail Interface User-Agent: Cyrus-JMAP/3.7.0-alpha0-841-g7899e99a45-fm-20220811.002-g7899e99a Mime-Version: 1.0 Message-Id: <70e68b28-73fa-4d16-a135-cbb03ea09d35@betaapp.fastmail.com> In-Reply-To: <4e0eff48-4a3e-4f0e-9ed2-d01ec38442a5@www.fastmail.com> References: <4e0eff48-4a3e-4f0e-9ed2-d01ec38442a5@www.fastmail.com> Date: Fri, 26 Aug 2022 17:53:28 +0200 From: "Greg Hurrell" To: git@vger.kernel.org Cc: "Phillip Wood" Subject: Re: Bad behavior in xhistogram.c in the face of hash collisions? Content-Type: text/plain Precedence: bulk List-ID: X-Mailing-List: git@vger.kernel.org On Mon, Aug 16, 2021, at 2:40 PM, Greg Hurrell wrote: > > I think I may have found a bug in the histogram diff algorithm that > manifests when there is a hash collision. This behavior seems to exist > in the JGit implimentation (https://git.io/J0Ud8) too, and was brought > across with the port-to-C in 8c912eea94a2. Thought I had better bump the thread as I did a fire-and-forget on it a year ago and never followed up because I wasn't super confident about my findings. I'd be interested in corroboration of my analysis, to see whether there really is a bug there. Not quoting my entire email here so as to keep things brief, but the original can be seen at: https://public-inbox.org/git/4e0eff48-4a3e-4f0e-9ed2-d01ec38442a5@www.fastmail.com/ (Phillip, CC'ing you for an opinion because I see you have made a few changes to xdiff/xhistogram.c relatively recently.) Best wishes, Greg