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Merge branch 'jk/duplicate-objects-in-packs'
A packfile that stores the same object more than once is broken and will be rejected by "git index-pack" that is run when receiving data over the wire. * jk/duplicate-objects-in-packs: t5308: check that index-pack --strict detects duplicate objects test index-pack on packs with recoverable delta cycles add tests for indexing packs with delta cycles sha1-lookup: handle duplicate keys with GIT_USE_LOOKUP test-sha1: add a binary output mode
This commit is contained in:
Junio C Hamano
commit
6c34560053
5 changed files with 316 additions and 3 deletions
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@ -204,7 +204,54 @@ int sha1_entry_pos(const void *table,
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* byte 0 thru (ofs-1) are the same between
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* lo and hi; ofs is the first byte that is
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* different.
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*
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* If ofs==20, then no bytes are different,
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* meaning we have entries with duplicate
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* keys. We know that we are in a solid run
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* of this entry (because the entries are
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* sorted, and our lo and hi are the same,
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* there can be nothing but this single key
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* in between). So we can stop the search.
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* Either one of these entries is it (and
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* we do not care which), or we do not have
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* it.
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*
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* Furthermore, we know that one of our
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* endpoints must be the edge of the run of
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* duplicates. For example, given this
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* sequence:
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*
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* idx 0 1 2 3 4 5
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* key A C C C C D
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*
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* If we are searching for "B", we might
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* hit the duplicate run at lo=1, hi=3
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* (e.g., by first mi=3, then mi=0). But we
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* can never have lo > 1, because B < C.
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* That is, if our key is less than the
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* run, we know that "lo" is the edge, but
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* we can say nothing of "hi". Similarly,
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* if our key is greater than the run, we
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* know that "hi" is the edge, but we can
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* say nothing of "lo".
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*
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* Therefore if we do not find it, we also
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* know where it would go if it did exist:
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* just on the far side of the edge that we
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* know about.
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*/
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if (ofs == 20) {
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mi = lo;
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mi_key = base + elem_size * mi + key_offset;
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cmp = memcmp(mi_key, key, 20);
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if (!cmp)
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return mi;
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if (cmp < 0)
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return -1 - hi;
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else
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return -1 - lo;
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}
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hiv = hi_key[ofs_0];
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if (ofs_0 < 19)
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hiv = (hiv << 8) | hi_key[ofs_0+1];
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100
t/lib-pack.sh
Normal file
100
t/lib-pack.sh
Normal file
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@ -0,0 +1,100 @@
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#!/bin/sh
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#
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# Support routines for hand-crafting weird or malicious packs.
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#
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# You can make a complete pack like:
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#
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# pack_header 2 >foo.pack &&
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# pack_obj e69de29bb2d1d6434b8b29ae775ad8c2e48c5391 >>foo.pack &&
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# pack_obj e68fe8129b546b101aee9510c5328e7f21ca1d18 >>foo.pack &&
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# pack_trailer foo.pack
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# Print the big-endian 4-byte octal representation of $1
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uint32_octal () {
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n=$1
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printf '\%o' $(($n / 16777216)); n=$((n % 16777216))
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printf '\%o' $(($n / 65536)); n=$((n % 65536))
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printf '\%o' $(($n / 256)); n=$((n % 256))
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printf '\%o' $(($n ));
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}
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# Print the big-endian 4-byte binary representation of $1
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uint32_binary () {
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printf "$(uint32_octal "$1")"
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}
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# Print a pack header, version 2, for a pack with $1 objects
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pack_header () {
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printf 'PACK' &&
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printf '\0\0\0\2' &&
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uint32_binary "$1"
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}
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# Print the pack data for object $1, as a delta against object $2 (or as a full
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# object if $2 is missing or empty). The output is suitable for including
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# directly in the packfile, and represents the entirety of the object entry.
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# Doing this on the fly (especially picking your deltas) is quite tricky, so we
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# have hardcoded some well-known objects. See the case statements below for the
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# complete list.
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pack_obj () {
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case "$1" in
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# empty blob
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e69de29bb2d1d6434b8b29ae775ad8c2e48c5391)
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case "$2" in
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'')
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printf '\060\170\234\003\0\0\0\0\1'
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return
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;;
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esac
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;;
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# blob containing "\7\76"
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e68fe8129b546b101aee9510c5328e7f21ca1d18)
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case "$2" in
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'')
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printf '\062\170\234\143\267\3\0\0\116\0\106'
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return
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;;
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01d7713666f4de822776c7622c10f1b07de280dc)
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printf '\165\1\327\161\66\146\364\336\202\47\166' &&
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printf '\307\142\54\20\361\260\175\342\200\334\170' &&
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printf '\234\143\142\142\142\267\003\0\0\151\0\114'
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return
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;;
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esac
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;;
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# blob containing "\7\0"
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01d7713666f4de822776c7622c10f1b07de280dc)
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case "$2" in
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'')
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printf '\062\170\234\143\147\0\0\0\20\0\10'
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return
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;;
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e68fe8129b546b101aee9510c5328e7f21ca1d18)
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printf '\165\346\217\350\22\233\124\153\20\32\356' &&
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printf '\225\20\305\62\216\177\41\312\35\30\170\234' &&
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printf '\143\142\142\142\147\0\0\0\53\0\16'
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return
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;;
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esac
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;;
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esac
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echo >&2 "BUG: don't know how to print $1${2:+ (from $2)}"
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return 1
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}
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# Compute and append pack trailer to "$1"
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pack_trailer () {
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test-sha1 -b <"$1" >trailer.tmp &&
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cat trailer.tmp >>"$1" &&
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rm -f trailer.tmp
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}
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# Remove any existing packs to make sure that
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# whatever we index next will be the pack that we
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# actually use.
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clear_packs () {
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rm -f .git/objects/pack/*
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}
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80
t/t5308-pack-detect-duplicates.sh
Executable file
80
t/t5308-pack-detect-duplicates.sh
Executable file
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@ -0,0 +1,80 @@
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#!/bin/sh
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test_description='handling of duplicate objects in incoming packfiles'
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. ./test-lib.sh
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. "$TEST_DIRECTORY"/lib-pack.sh
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# The sha1s we have in our pack. It's important that these have the same
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# starting byte, so that they end up in the same fanout section of the index.
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# That lets us make sure we are exercising the binary search with both sets.
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LO_SHA1=e68fe8129b546b101aee9510c5328e7f21ca1d18
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HI_SHA1=e69de29bb2d1d6434b8b29ae775ad8c2e48c5391
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# And here's a "missing sha1" which will produce failed lookups. It must also
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# be in the same fanout section, and should be between the two (so that during
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# our binary search, we are sure to end up looking at one or the other of the
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# duplicate runs).
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MISSING_SHA1='e69d000000000000000000000000000000000000'
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# git will never intentionally create packfiles with
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# duplicate objects, so we have to construct them by hand.
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#
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# $1 is the name of the packfile to create
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#
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# $2 is the number of times to duplicate each object
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create_pack () {
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pack_header "$((2 * $2))" >"$1" &&
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for i in $(test_seq 1 "$2"); do
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pack_obj $LO_SHA1 &&
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pack_obj $HI_SHA1
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done >>"$1" &&
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pack_trailer "$1"
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}
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# double-check that create_pack actually works
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test_expect_success 'pack with no duplicates' '
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create_pack no-dups.pack 1 &&
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git index-pack --stdin <no-dups.pack
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'
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test_expect_success 'index-pack will allow duplicate objects by default' '
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clear_packs &&
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create_pack dups.pack 100 &&
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git index-pack --stdin <dups.pack
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'
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test_expect_success 'create batch-check test vectors' '
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cat >input <<-EOF &&
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$LO_SHA1
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$HI_SHA1
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$MISSING_SHA1
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EOF
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cat >expect <<-EOF
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$LO_SHA1 blob 2
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$HI_SHA1 blob 0
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$MISSING_SHA1 missing
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EOF
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'
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test_expect_success 'lookup in duplicated pack (binary search)' '
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git cat-file --batch-check <input >actual &&
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test_cmp expect actual
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'
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test_expect_success 'lookup in duplicated pack (GIT_USE_LOOKUP)' '
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(
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GIT_USE_LOOKUP=1 &&
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export GIT_USE_LOOKUP &&
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git cat-file --batch-check <input >actual
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) &&
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test_cmp expect actual
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'
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test_expect_success 'index-pack can reject packs with duplicates' '
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clear_packs &&
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create_pack dups.pack 2 &&
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test_must_fail git index-pack --strict --stdin <dups.pack &&
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test_expect_code 1 git cat-file -e $LO_SHA1
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'
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test_done
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77
t/t5309-pack-delta-cycles.sh
Executable file
77
t/t5309-pack-delta-cycles.sh
Executable file
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@ -0,0 +1,77 @@
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#!/bin/sh
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test_description='test index-pack handling of delta cycles in packfiles'
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. ./test-lib.sh
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. "$TEST_DIRECTORY"/lib-pack.sh
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# Two similar-ish objects that we have computed deltas between.
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A=01d7713666f4de822776c7622c10f1b07de280dc
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B=e68fe8129b546b101aee9510c5328e7f21ca1d18
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# double-check our hand-constucted packs
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test_expect_success 'index-pack works with a single delta (A->B)' '
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clear_packs &&
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{
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pack_header 2 &&
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pack_obj $A $B &&
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pack_obj $B
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} >ab.pack &&
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pack_trailer ab.pack &&
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git index-pack --stdin <ab.pack &&
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git cat-file -t $A &&
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git cat-file -t $B
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'
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test_expect_success 'index-pack works with a single delta (B->A)' '
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clear_packs &&
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{
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pack_header 2 &&
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pack_obj $A &&
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pack_obj $B $A
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} >ba.pack &&
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pack_trailer ba.pack &&
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git index-pack --stdin <ba.pack &&
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git cat-file -t $A &&
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git cat-file -t $B
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'
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test_expect_success 'index-pack detects missing base objects' '
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clear_packs &&
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{
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pack_header 1 &&
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pack_obj $A $B
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} >missing.pack &&
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pack_trailer missing.pack &&
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test_must_fail git index-pack --fix-thin --stdin <missing.pack
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'
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test_expect_success 'index-pack detects REF_DELTA cycles' '
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clear_packs &&
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{
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pack_header 2 &&
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pack_obj $A $B &&
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pack_obj $B $A
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} >cycle.pack &&
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pack_trailer cycle.pack &&
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test_must_fail git index-pack --fix-thin --stdin <cycle.pack
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'
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test_expect_failure 'failover to an object in another pack' '
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clear_packs &&
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git index-pack --stdin <ab.pack &&
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git index-pack --stdin --fix-thin <cycle.pack
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'
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test_expect_failure 'failover to a duplicate object in the same pack' '
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clear_packs &&
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{
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pack_header 3 &&
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pack_obj $A $B &&
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pack_obj $B $A &&
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pack_obj $A
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} >recoverable.pack &&
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pack_trailer recoverable.pack &&
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git index-pack --fix-thin --stdin <recoverable.pack
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'
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test_done
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15
test-sha1.c
15
test-sha1.c
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@ -5,10 +5,15 @@ int main(int ac, char **av)
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git_SHA_CTX ctx;
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unsigned char sha1[20];
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unsigned bufsz = 8192;
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int binary = 0;
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char *buffer;
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if (ac == 2)
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bufsz = strtoul(av[1], NULL, 10) * 1024 * 1024;
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if (ac == 2) {
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if (!strcmp(av[1], "-b"))
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binary = 1;
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else
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bufsz = strtoul(av[1], NULL, 10) * 1024 * 1024;
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}
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if (!bufsz)
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bufsz = 8192;
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@ -42,6 +47,10 @@ int main(int ac, char **av)
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git_SHA1_Update(&ctx, buffer, this_sz);
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}
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git_SHA1_Final(sha1, &ctx);
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puts(sha1_to_hex(sha1));
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if (binary)
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fwrite(sha1, 1, 20, stdout);
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else
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puts(sha1_to_hex(sha1));
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exit(0);
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}
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