From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.2 (2018-09-13) on dcvr.yhbt.net X-Spam-Level: X-Spam-ASN: AS3215 2.6.0.0/16 X-Spam-Status: No, score=-3.8 required=3.0 tests=AWL,BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,FREEMAIL_FORGED_FROMDOMAIN,FREEMAIL_FROM, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_HELO_NONE, SPF_PASS,T_SCC_BODY_TEXT_LINE shortcircuit=no autolearn=ham autolearn_force=no version=3.4.2 Received: from out1.vger.email (out1.vger.email [IPv6:2620:137:e000::1:20]) by dcvr.yhbt.net (Postfix) with ESMTP id 537F21F4D7 for ; Sun, 12 Jun 2022 06:18:50 +0000 (UTC) Authentication-Results: dcvr.yhbt.net; dkim=pass (1024-bit key; secure) header.d=web.de header.i=@web.de header.b="Cwz+OT5j"; dkim-atps=neutral Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S234511AbiFLGSs (ORCPT ); Sun, 12 Jun 2022 02:18:48 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:48820 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229664AbiFLGSq (ORCPT ); Sun, 12 Jun 2022 02:18:46 -0400 Received: from mout.web.de (mout.web.de [212.227.15.14]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 4D3F539BA6 for ; Sat, 11 Jun 2022 23:18:44 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=web.de; s=dbaedf251592; t=1655014701; bh=1UVCC78FdXD4x06vNF2gJTXUHfIxiKSYmgoRCp6h724=; h=X-UI-Sender-Class:Date:Subject:From:To:Cc:References:In-Reply-To; b=Cwz+OT5js8HpT/YkR5JHgbnKQDzAg+nHc8RbDEp43HVIGzCMpbJcGqyhjlHtCwqsP oZrmSvBILy/yzpdambaA18SPdJr3x1YnTvBZkKkUbMNUKd6AcsQlSxJSdj2KY5jKnI WoY5g0hnqWwh0ozWaajfEowH+mRyCwQDOInv/0cA= X-UI-Sender-Class: c548c8c5-30a9-4db5-a2e7-cb6cb037b8f9 Received: from [192.168.178.29] ([79.203.31.99]) by smtp.web.de (mrweb005 [213.165.67.108]) with ESMTPSA (Nemesis) id 1M9ZZo-1o3aJc3Ra8-005kiY; Sun, 12 Jun 2022 08:18:20 +0200 Message-ID: <0a6877c3-07f2-b0e2-f23c-9ea4c588e8a5@web.de> Date: Sun, 12 Jun 2022 08:18:20 +0200 MIME-Version: 1.0 User-Agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10.15; rv:91.0) Gecko/20100101 Thunderbird/91.10.0 Subject: [PATCH v3 4/5] archive-tar: use OS_CODE 3 (Unix) for internal gzip Content-Language: en-US From: =?UTF-8?Q?Ren=c3=a9_Scharfe?= To: git@vger.kernel.org Cc: Junio C Hamano , Johannes Schindelin , Rohit Ashiwal , =?UTF-8?B?w4Z2YXIgQXJuZmrDtnLDsCBCamFybWFzb24=?= , Jeff King , "brian m . carlson" References: <217a2f4d-4fc2-aaed-f5c2-1b7e134b046d@web.de> In-Reply-To: <217a2f4d-4fc2-aaed-f5c2-1b7e134b046d@web.de> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: quoted-printable X-Provags-ID: V03:K1:ZMD5m2x3NvG36FYnYGrEoWqUFYtakQdpuu8kP51VxxIHzxam956 DQwisIObJyQcUjeC+VFWN1fwqObuUqCyu5TvdAKjq3LZNaqGMHXL9izBu+OdoAJaz3i2ZBB 8CaOizSt1JwkhglnCWdMeG1zJF5llSoSOETk2UnqpYN/n5Nb+Qf4rUlsnt8ph/72//PKl4E gOctF/R7mkTC4euKm34Wg== X-UI-Out-Filterresults: notjunk:1;V03:K0:gF9pEg64btI=:sCd1qBLCt/X/oKw05HKrpW Knt4kxmgGT+KalDljIbobWNDfh+bXqF+lnhe5WozmLVaV18FMwQ36Ab2P3AK+IMsmrMG2Le03 FoGr1MbnIrKSL95n9EVv2PxxIaLEm0UIeqstH2TImCFJBOdi78HQio8+UJIYjLD0r/WV/CGOu bZell81ypIH+GEBnGFYfdSgu1LSN6wfl+ANaHj/7SiEYHJ/duB/xkxn/WT453UgJaBjAB3yVp 61xWKcQ9GbyUbhlcT6yJRmIZqxYYKc4VRZ3/PX69SaCgHfFXirNAbTkyjpMDoWsbeDwRKggrs l24/D2nx+xvlyonPEFpTLxzTALVszPUe8NWPk/NPqaG9hLckvu7ebBMQrDdoPjh6pdeBzOgej BqCLdUtXwVKWU82xmlihn0lsimpvjiuyLj0eE9j9LFfjKOfTy6q/4V6GgyjapMXvH/FEMKCpz ZXChuuIntirgkOCieNSa4xduBtq9f7TRrzjxWsBWjJJPJsegWlaObgRuVx7PYd0QOf1QCkmSW 3KJuxvqN/qWdEJsqN4k+8IaFTP9MuiOPVHGiV113UkQwaj9wAmMA1ji1PzZhna9gVfmrk6jbk b1P8fvPVnf+MPb2qQTYrKEJhhFB1DwhKQJsiDKFwjQHFOsO9EKBdcyhRZ5VbgEi5UsxN+MS0Q H/Iu9WOM0k9pdZYG8iuIig7Pn/tgiJA/VQjjOUtaCqSxpf1k2Rv3hVZFw88UU0BH2IHVVM+cI B06/DFjzyy3ZRSuAhVm66lLnLVkP0YkyfKMYjaXeKd6I93xt22qKa0M/pthgnZHEZtozuHO/L TPkO5B++Z34YLsDxcqThiopNJ7O4mvcJTaXcZod6yiXBVcTCeeGL2O1d2Z5E2IP+IZ8enyzNx pLnPTaZqzT1z6bYC89Z7xb/S3gWaZvBAsJJ5IyV/Te5gBVqzm3lk3HXJa1YE6C1MuVBIpYixo XviY/6nQuWIj0lXuT8YCU0K3yJs5KscXA0PG9UUy9i5tppBAmvpMsr6YU4VndtYnLCpZw7Uea gF6GS9x3rg1/RYhlfqUemeBycOc1jKBkJPr2wLb5R4pdtgs8Xir/PbLcy1lBOhSRT8njASVY1 WNUF4va6zWpsm2RB0owIDf6TiI698dxnjrA Precedence: bulk List-ID: X-Mailing-List: git@vger.kernel.org gzip(1) encodes the OS it runs on in the 10th byte of its output. It uses the following OS_CODE values according to its tailor.h [1]: 0 - MS-DOS 3 - UNIX 5 - Atari ST 6 - OS/2 10 - TOPS-20 11 - Windows NT The gzip.exe that comes with Git for Windows uses OS_CODE 3 for some reason, so this value is used on practically all supported platforms when generating tgz archives using gzip(1). Zlib uses a bigger set of values according to its zutil.h [2], aligned with section 4.4.2 of the ZIP specification, APPNOTE.txt [3]: 0 - MS-DOS 1 - Amiga 3 - UNIX 4 - VM/CMS 5 - Atari ST 6 - OS/2 7 - Macintosh 8 - Z-System 10 - Windows NT 11 - MVS (OS/390 - Z/OS) 13 - Acorn Risc 16 - BeOS 18 - OS/400 19 - OS X (Darwin) Thus the internal gzip implementation in archive-tar.c sets different OS_CODE header values on major platforms Windows and macOS. Git for Windows uses its own zlib-based variant since v2.20.1 by default and thus embeds OS_CODE 10 in tgz archives. The tar archive for a commit is generated consistently on all systems (by the same Git version). The OS_CODE in the gzip header does not influence extraction. Avoid leaking OS information and make tgz archives constistent and reproducable (with the same Git and libz versions) by using OS_CODE 3 everywhere. NB: The function deflateSetHeader() was introduced by zlib 1.2.2.1, released 2004-10-31. At least on macOS 12.4 this produces the same output as gzip(1) for the examples I tried: # before $ git -c tar.tgz.command=3D'git archive gzip' archive --format=3Dtgz v2= .36.0 | shasum 3abbffb40b7c63cf9b7d91afc682f11682f80759 - # with this patch $ git -c tar.tgz.command=3D'git archive gzip' archive --format=3Dtgz v2= .36.0 | shasum dc6dc6ba9636d522799085d0d77ab6a110bcc141 - $ git archive --format=3Dtar v2.36.0 | gzip -cn | shasum dc6dc6ba9636d522799085d0d77ab6a110bcc141 - [1] https://git.savannah.gnu.org/cgit/gzip.git/tree/tailor.h [2] https://github.com/madler/zlib/blob/master/zutil.h [3] https://pkware.cachefly.net/webdocs/casestudies/APPNOTE.TXT Signed-off-by: Ren=C3=A9 Scharfe =2D-- Perhaps makes sense for remote-curl as well (out of scope of this series)? archive-tar.c | 9 +++++++++ 1 file changed, 9 insertions(+) diff --git a/archive-tar.c b/archive-tar.c index 53d0ef685c..bf7e321e0e 100644 =2D-- a/archive-tar.c +++ b/archive-tar.c @@ -460,6 +460,14 @@ static void tgz_write_block(const void *data) static const char internal_gzip_command[] =3D "git archive gzip"; +static void tgz_set_os(git_zstream *strm, int os) +{ +#if ZLIB_VERNUM >=3D 0x1221 + struct gz_header_s gzhead =3D { .os =3D os }; + deflateSetHeader(&strm->z, &gzhead); +#endif +} + static int write_tar_filter_archive(const struct archiver *ar, struct archiver_args *args) { @@ -473,6 +481,7 @@ static int write_tar_filter_archive(const struct archi= ver *ar, if (!strcmp(ar->filter_command, internal_gzip_command)) { write_block =3D tgz_write_block; git_deflate_init_gzip(&gzstream, args->compression_level); + tgz_set_os(&gzstream, 3); /* Unix, for reproducibility */ gzstream.next_out =3D outbuf; gzstream.avail_out =3D sizeof(outbuf); =2D- 2.36.1