[PATCH 3/6] add tests for indexing packs with delta cycles
- From
Jeff King <peff@peff.net>
- Date
- Aug 22, 2013, 23:14 UTC
- Message-ID
- <20130822231440.GC17060@sigill.intra.peff.net>
- In-Reply-To
- <20130822231215.GA16978@sigill.intra.peff.net>
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 <peff@peff.net> --- 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 61c5d19..e028c40 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..9b3f2c3 --- /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 +. ../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 <ab.pack && + git cat-file -t $A && + git cat-file -t $B +' + +test_expect_success 'index-pack works with a single delta (B->A)' ' + clear_packs && + { + pack_header 2 && + pack_obj $A && + pack_obj $B $A + } >ba.pack && + pack_trailer ba.pack && + git index-pack --stdin <ba.pack && + git cat-file -t $A && + git cat-file -t $B +' + +test_expect_success 'index-pack detects missing base objects' ' + clear_packs && + { + pack_header 1 && + pack_obj $A $B + } >missing.pack && + pack_trailer missing.pack && + test_must_fail git index-pack --fix-thin --stdin <missing.pack +' + +test_expect_success 'index-pack detects REF_DELTA cycles' ' + clear_packs && + { + pack_header 2 && + pack_obj $A $B && + pack_obj $B $A + } >cycle.pack && + pack_trailer cycle.pack && + test_must_fail git index-pack --fix-thin --stdin <cycle.pack +' + +test_done
-- 1.8.4.rc2.28.g6bb5f3f