From mboxrd@z Thu Jan 1 00:00:00 1970 From: Jeff King Subject: [PATCH 3/6] add tests for indexing packs with delta cycles Date: Fri, 23 Aug 2013 20:02:31 -0400 Message-ID: <20130824000231.GC25833@sigill.intra.peff.net> References: <20130824000111.GA20255@sigill.intra.peff.net> Mime-Version: 1.0 Content-Type: text/plain; charset=utf-8 Cc: Git Mailing List , Duy Nguyen , "Shawn O. Pearce" , Nicolas Pitre To: Junio C Hamano X-From: git-owner@vger.kernel.org Sat Aug 24 02:02:42 2013 Return-path: Envelope-to: gcvg-git-2@plane.gmane.org Received: from vger.kernel.org ([209.132.180.67]) by plane.gmane.org with esmtp (Exim 4.69) (envelope-from ) id 1VD1JO-0001sa-N0 for gcvg-git-2@plane.gmane.org; Sat, 24 Aug 2013 02:02:39 +0200 Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754845Ab3HXACe (ORCPT ); Fri, 23 Aug 2013 20:02:34 -0400 Received: from cloud.peff.net ([50.56.180.127]:41492 "EHLO peff.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754492Ab3HXACe (ORCPT ); Fri, 23 Aug 2013 20:02:34 -0400 Received: (qmail 30031 invoked by uid 102); 24 Aug 2013 00:02:34 -0000 Received: from c-71-63-4-13.hsd1.va.comcast.net (HELO sigill.intra.peff.net) (71.63.4.13) (smtp-auth username relayok, mechanism cram-md5) by peff.net (qpsmtpd/0.84) with ESMTPA; Fri, 23 Aug 2013 19:02:34 -0500 Received: by sigill.intra.peff.net (sSMTP sendmail emulation); Fri, 23 Aug 2013 20:02:31 -0400 Content-Disposition: inline In-Reply-To: <20130824000111.GA20255@sigill.intra.peff.net> Sender: git-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: git@vger.kernel.org Archived-At: If we receive a broken or malicious pack from a remote, we will feed it to index-pack. As index-pack processes the objects as a stream, reconstructing and hashing each object to get its name, it is not very susceptible to doing the wrong with bad data (it simply notices that the data is bogus and aborts). However, one question raised on the list is whether it could be susceptible to problems during the delta-resolution phase. In particular, can a cycle in the packfile deltas cause us to go into an infinite loop or cause any other problem? The answer is no. We cannot have a cycle of delta-base offsets, because they go only in one direction (the OFS_DELTA object mentions its base by an offset towards the beginning of the file, and we explicitly reject negative offsets). We can have a cycle of REF_DELTA objects, which refer to base objects by sha1 name. However, index-pack does not know these sha1 names ahead of time; it has to reconstruct the objects to get their names, and it cannot do so if there is a delta cycle (in other words, it does not even realize there is a cycle, but only that there are items that cannot be resolved). Even though we can reason out that index-pack should handle this fine, let's add a few tests to make sure it behaves correctly. Signed-off-by: Jeff King Acked-by: Nicolas Pitre --- t/lib-pack.sh | 22 +++++++++++++++++ t/t5309-pack-delta-cycles.sh | 59 ++++++++++++++++++++++++++++++++++++++++++++ 2 files changed, 81 insertions(+) create mode 100755 t/t5309-pack-delta-cycles.sh diff --git a/t/lib-pack.sh b/t/lib-pack.sh index fecd5a0..7e8685b 100644 --- a/t/lib-pack.sh +++ b/t/lib-pack.sh @@ -55,6 +55,28 @@ pack_obj () { printf '\062\170\234\143\267\3\0\0\116\0\106' return ;; + 01d7713666f4de822776c7622c10f1b07de280dc) + printf '\165\1\327\161\66\146\364\336\202\47\166' && + printf '\307\142\54\20\361\260\175\342\200\334\170' && + printf '\234\143\142\142\142\267\003\0\0\151\0\114' + return + ;; + esac + ;; + + # blob containing "\7\0" + 01d7713666f4de822776c7622c10f1b07de280dc) + case "$2" in + '') + printf '\062\170\234\143\147\0\0\0\20\0\10' + return + ;; + e68fe8129b546b101aee9510c5328e7f21ca1d18) + printf '\165\346\217\350\22\233\124\153\20\32\356' && + printf '\225\20\305\62\216\177\41\312\35\30\170\234' && + printf '\143\142\142\142\147\0\0\0\53\0\16' + return + ;; esac ;; esac diff --git a/t/t5309-pack-delta-cycles.sh b/t/t5309-pack-delta-cycles.sh new file mode 100755 index 0000000..1640bf7 --- /dev/null +++ b/t/t5309-pack-delta-cycles.sh @@ -0,0 +1,59 @@ +#!/bin/sh + +test_description='test index-pack handling of delta cycles in packfiles' +. ./test-lib.sh +. "$TEST_DIRECTORY"/lib-pack.sh + +# Two similar-ish objects that we have computed deltas between. +A=01d7713666f4de822776c7622c10f1b07de280dc +B=e68fe8129b546b101aee9510c5328e7f21ca1d18 + +# double-check our hand-constucted packs +test_expect_success 'index-pack works with a single delta (A->B)' ' + clear_packs && + { + pack_header 2 && + pack_obj $A $B && + pack_obj $B + } >ab.pack && + pack_trailer ab.pack && + git index-pack --stdin A)' ' + clear_packs && + { + pack_header 2 && + pack_obj $A && + pack_obj $B $A + } >ba.pack && + pack_trailer ba.pack && + git index-pack --stdin missing.pack && + pack_trailer missing.pack && + test_must_fail git index-pack --fix-thin --stdin cycle.pack && + pack_trailer cycle.pack && + test_must_fail git index-pack --fix-thin --stdin