From 3b910d0c5ee3a06ba0463f97ccf59815e7b37e29 Mon Sep 17 00:00:00 2001 From: Jeff King Date: Fri, 23 Aug 2013 20:02:31 -0400 Subject: add tests for indexing packs with delta cycles 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 Signed-off-by: Junio C Hamano --- 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 (limited to 't') diff --git a/t/lib-pack.sh b/t/lib-pack.sh index fecd5a0279..7e8685b44c 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 "$2" in + '') + printf '\062\170\234\143\147\0\0\0\20\0\10' + return + ;; + e68fe8129b546b101aee9510c5328e7f21ca1d18) + printf '\165\346\217\350\22\233\124\153\20\32\356' && + printf '\225\20\305\62\216\177\41\312\35\30\170\234' && + printf '\143\142\142\142\147\0\0\0\53\0\16' + return + ;; esac ;; esac diff --git a/t/t5309-pack-delta-cycles.sh b/t/t5309-pack-delta-cycles.sh new file mode 100755 index 0000000000..1640bf7764 --- /dev/null +++ b/t/t5309-pack-delta-cycles.sh @@ -0,0 +1,59 @@ +#!/bin/sh + +test_description='test index-pack handling of delta cycles in packfiles' +. ./test-lib.sh +. "$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