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https://github.com/git/git.git
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1190a1acf8
Our current scheme for naming packfiles is to calculate the sha1 hash of the sorted list of objects contained in the packfile. This gives us a unique name, so we are reasonably sure that two packs with the same name will contain the same objects. It does not, however, tell us that two such packs have the exact same bytes. This makes things awkward if we repack the same set of objects. Due to run-to-run variations, the bytes may not be identical (e.g., changed zlib or git versions, different source object reuse due to new packs in the repository, or even different deltas due to races during a multi-threaded delta search). In theory, this could be helpful to a program that cares that the packfile contains a certain set of objects, but does not care about the particular representation. In practice, no part of git makes use of that, and in many cases it is potentially harmful. For example, if a dumb http client fetches the .idx file, it must be sure to get the exact .pack that matches it. Similarly, a partial transfer of a .pack file cannot be safely resumed, as the actual bytes may have changed. This could also affect a local client which opened the .idx and .pack files, closes the .pack file (due to memory or file descriptor limits), and then re-opens a changed packfile. In all of these cases, git can detect the problem, as we have the sha1 of the bytes themselves in the pack trailer (which we verify on transfer), and the .idx file references the trailer from the matching packfile. But it would be simpler and more efficient to actually get the correct bytes, rather than noticing the problem and having to restart the operation. This patch simply uses the pack trailer sha1 as the pack name. It should be similarly unique, but covers the exact representation of the objects. Other parts of git should not care, as the pack name is returned by pack-objects and is essentially opaque. One test needs to be updated, because it actually corrupts a pack and expects that re-packing the corrupted bytes will use the same name. It won't anymore, but we can easily just use the name that pack-objects hands back. Signed-off-by: Jeff King <peff@peff.net> Signed-off-by: Junio C Hamano <gitster@pobox.com>
246 lines
8.7 KiB
Bash
Executable file
246 lines
8.7 KiB
Bash
Executable file
#!/bin/sh
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#
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# Copyright (c) 2007 Nicolas Pitre
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#
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test_description='pack index with 64-bit offsets and object CRC'
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. ./test-lib.sh
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test_expect_success \
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'setup' \
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'rm -rf .git &&
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git init &&
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git config pack.threads 1 &&
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i=1 &&
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while test $i -le 100
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do
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iii=`printf '%03i' $i`
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test-genrandom "bar" 200 > wide_delta_$iii &&
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test-genrandom "baz $iii" 50 >> wide_delta_$iii &&
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test-genrandom "foo"$i 100 > deep_delta_$iii &&
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test-genrandom "foo"`expr $i + 1` 100 >> deep_delta_$iii &&
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test-genrandom "foo"`expr $i + 2` 100 >> deep_delta_$iii &&
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echo $iii >file_$iii &&
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test-genrandom "$iii" 8192 >>file_$iii &&
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git update-index --add file_$iii deep_delta_$iii wide_delta_$iii &&
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i=`expr $i + 1` || return 1
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done &&
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{ echo 101 && test-genrandom 100 8192; } >file_101 &&
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git update-index --add file_101 &&
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tree=`git write-tree` &&
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commit=`git commit-tree $tree </dev/null` && {
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echo $tree &&
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git ls-tree $tree | sed -e "s/.* \\([0-9a-f]*\\) .*/\\1/"
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} >obj-list &&
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git update-ref HEAD $commit'
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test_expect_success \
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'pack-objects with index version 1' \
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'pack1=$(git pack-objects --index-version=1 test-1 <obj-list) &&
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git verify-pack -v "test-1-${pack1}.pack"'
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test_expect_success \
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'pack-objects with index version 2' \
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'pack2=$(git pack-objects --index-version=2 test-2 <obj-list) &&
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git verify-pack -v "test-2-${pack2}.pack"'
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test_expect_success \
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'both packs should be identical' \
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'cmp "test-1-${pack1}.pack" "test-2-${pack2}.pack"'
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test_expect_success \
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'index v1 and index v2 should be different' \
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'! cmp "test-1-${pack1}.idx" "test-2-${pack2}.idx"'
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test_expect_success \
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'index-pack with index version 1' \
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'git index-pack --index-version=1 -o 1.idx "test-1-${pack1}.pack"'
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test_expect_success \
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'index-pack with index version 2' \
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'git index-pack --index-version=2 -o 2.idx "test-1-${pack1}.pack"'
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test_expect_success \
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'index-pack results should match pack-objects ones' \
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'cmp "test-1-${pack1}.idx" "1.idx" &&
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cmp "test-2-${pack2}.idx" "2.idx"'
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test_expect_success 'index-pack --verify on index version 1' '
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git index-pack --verify "test-1-${pack1}.pack"
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'
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test_expect_success 'index-pack --verify on index version 2' '
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git index-pack --verify "test-2-${pack2}.pack"
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'
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test_expect_success \
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'pack-objects --index-version=2, is not accepted' \
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'test_must_fail git pack-objects --index-version=2, test-3 <obj-list'
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test_expect_success \
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'index v2: force some 64-bit offsets with pack-objects' \
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'pack3=$(git pack-objects --index-version=2,0x40000 test-3 <obj-list)'
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if msg=$(git verify-pack -v "test-3-${pack3}.pack" 2>&1) ||
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! (echo "$msg" | grep "pack too large .* off_t")
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then
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test_set_prereq OFF64_T
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else
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say "# skipping tests concerning 64-bit offsets"
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fi
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test_expect_success OFF64_T \
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'index v2: verify a pack with some 64-bit offsets' \
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'git verify-pack -v "test-3-${pack3}.pack"'
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test_expect_success OFF64_T \
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'64-bit offsets: should be different from previous index v2 results' \
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'! cmp "test-2-${pack2}.idx" "test-3-${pack3}.idx"'
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test_expect_success OFF64_T \
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'index v2: force some 64-bit offsets with index-pack' \
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'git index-pack --index-version=2,0x40000 -o 3.idx "test-1-${pack1}.pack"'
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test_expect_success OFF64_T \
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'64-bit offsets: index-pack result should match pack-objects one' \
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'cmp "test-3-${pack3}.idx" "3.idx"'
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test_expect_success OFF64_T 'index-pack --verify on 64-bit offset v2 (cheat)' '
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# This cheats by knowing which lower offset should still be encoded
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# in 64-bit representation.
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git index-pack --verify --index-version=2,0x40000 "test-3-${pack3}.pack"
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'
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test_expect_success OFF64_T 'index-pack --verify on 64-bit offset v2' '
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git index-pack --verify "test-3-${pack3}.pack"
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'
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# returns the object number for given object in given pack index
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index_obj_nr()
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{
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idx_file=$1
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object_sha1=$2
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nr=0
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git show-index < $idx_file |
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while read offs sha1 extra
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do
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nr=$(($nr + 1))
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test "$sha1" = "$object_sha1" || continue
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echo "$(($nr - 1))"
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break
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done
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}
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# returns the pack offset for given object as found in given pack index
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index_obj_offset()
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{
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idx_file=$1
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object_sha1=$2
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git show-index < $idx_file | grep $object_sha1 |
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( read offs extra && echo "$offs" )
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}
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test_expect_success \
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'[index v1] 1) stream pack to repository' \
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'git index-pack --index-version=1 --stdin < "test-1-${pack1}.pack" &&
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git prune-packed &&
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git count-objects | ( read nr rest && test "$nr" -eq 1 ) &&
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cmp "test-1-${pack1}.pack" ".git/objects/pack/pack-${pack1}.pack" &&
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cmp "test-1-${pack1}.idx" ".git/objects/pack/pack-${pack1}.idx"'
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test_expect_success \
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'[index v1] 2) create a stealth corruption in a delta base reference' \
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'# This test assumes file_101 is a delta smaller than 16 bytes.
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# It should be against file_100 but we substitute its base for file_099
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sha1_101=`git hash-object file_101` &&
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sha1_099=`git hash-object file_099` &&
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offs_101=`index_obj_offset 1.idx $sha1_101` &&
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nr_099=`index_obj_nr 1.idx $sha1_099` &&
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chmod +w ".git/objects/pack/pack-${pack1}.pack" &&
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dd of=".git/objects/pack/pack-${pack1}.pack" seek=$(($offs_101 + 1)) \
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if=".git/objects/pack/pack-${pack1}.idx" \
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skip=$((4 + 256 * 4 + $nr_099 * 24)) \
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bs=1 count=20 conv=notrunc &&
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git cat-file blob $sha1_101 > file_101_foo1'
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test_expect_success \
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'[index v1] 3) corrupted delta happily returned wrong data' \
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'test -f file_101_foo1 && ! cmp file_101 file_101_foo1'
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test_expect_success \
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'[index v1] 4) confirm that the pack is actually corrupted' \
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'test_must_fail git fsck --full $commit'
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test_expect_success \
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'[index v1] 5) pack-objects happily reuses corrupted data' \
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'pack4=$(git pack-objects test-4 <obj-list) &&
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test -f "test-4-${pack4}.pack"'
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test_expect_success \
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'[index v1] 6) newly created pack is BAD !' \
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'test_must_fail git verify-pack -v "test-4-${pack4}.pack"'
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test_expect_success \
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'[index v2] 1) stream pack to repository' \
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'rm -f .git/objects/pack/* &&
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git index-pack --index-version=2 --stdin < "test-1-${pack1}.pack" &&
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git prune-packed &&
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git count-objects | ( read nr rest && test "$nr" -eq 1 ) &&
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cmp "test-1-${pack1}.pack" ".git/objects/pack/pack-${pack1}.pack" &&
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cmp "test-2-${pack1}.idx" ".git/objects/pack/pack-${pack1}.idx"'
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test_expect_success \
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'[index v2] 2) create a stealth corruption in a delta base reference' \
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'# This test assumes file_101 is a delta smaller than 16 bytes.
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# It should be against file_100 but we substitute its base for file_099
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sha1_101=`git hash-object file_101` &&
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sha1_099=`git hash-object file_099` &&
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offs_101=`index_obj_offset 1.idx $sha1_101` &&
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nr_099=`index_obj_nr 1.idx $sha1_099` &&
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chmod +w ".git/objects/pack/pack-${pack1}.pack" &&
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dd of=".git/objects/pack/pack-${pack1}.pack" seek=$(($offs_101 + 1)) \
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if=".git/objects/pack/pack-${pack1}.idx" \
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skip=$((8 + 256 * 4 + $nr_099 * 20)) \
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bs=1 count=20 conv=notrunc &&
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git cat-file blob $sha1_101 > file_101_foo2'
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test_expect_success \
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'[index v2] 3) corrupted delta happily returned wrong data' \
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'test -f file_101_foo2 && ! cmp file_101 file_101_foo2'
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test_expect_success \
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'[index v2] 4) confirm that the pack is actually corrupted' \
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'test_must_fail git fsck --full $commit'
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test_expect_success \
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'[index v2] 5) pack-objects refuses to reuse corrupted data' \
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'test_must_fail git pack-objects test-5 <obj-list &&
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test_must_fail git pack-objects --no-reuse-object test-6 <obj-list'
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test_expect_success \
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'[index v2] 6) verify-pack detects CRC mismatch' \
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'rm -f .git/objects/pack/* &&
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git index-pack --index-version=2 --stdin < "test-1-${pack1}.pack" &&
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git verify-pack ".git/objects/pack/pack-${pack1}.pack" &&
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obj=`git hash-object file_001` &&
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nr=`index_obj_nr ".git/objects/pack/pack-${pack1}.idx" $obj` &&
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chmod +w ".git/objects/pack/pack-${pack1}.idx" &&
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printf xxxx | dd of=".git/objects/pack/pack-${pack1}.idx" conv=notrunc \
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bs=1 count=4 seek=$((8 + 256 * 4 + `wc -l <obj-list` * 20 + $nr * 4)) &&
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( while read obj
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do git cat-file -p $obj >/dev/null || exit 1
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done <obj-list ) &&
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test_must_fail git verify-pack ".git/objects/pack/pack-${pack1}.pack"
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'
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test_expect_success 'running index-pack in the object store' '
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rm -f .git/objects/pack/* &&
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cp test-1-${pack1}.pack .git/objects/pack/pack-${pack1}.pack &&
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(
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cd .git/objects/pack
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git index-pack pack-${pack1}.pack
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) &&
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test -f .git/objects/pack/pack-${pack1}.idx
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'
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test_done
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