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9514b0b226
When we see a delta command instructing us to copy bytes
from the base, we have to read the offset and size from the
delta stream. We do this without checking whether we're at
the end of the stream, meaning we may read past the end of
the buffer.
In practice this isn't exploitable in any interesting way
because:
1. Deltas are always in packfiles, so we have at least a
20-byte trailer that we'll end up reading.
2. The worst case is that we try to perform a nonsense
copy from the base object into the result, based on
whatever was in the pack stream next. In most cases
this will simply fail due to our bounds-checks against
the base or the result.
But even if you carefully constructed a pack stream for
which it succeeds, it wouldn't perform any delta
operation that you couldn't have simply included in a
non-broken form.
But obviously it's poor form to read past the end of the
buffer we've been given. Unfortunately there's no easy way
to do a single length check, since the number of bytes we
need depends on the number of bits set in the initial
command byte. So we'll just check each byte as we parse. We
can hide the complexity in a macro; it's ugly, but not as
ugly as writing out each individual conditional.
Signed-off-by: Jeff King <peff@peff.net>
Reviewed-by: Nicolas Pitre <nico@fluxnic.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
404 lines
14 KiB
Bash
Executable file
404 lines
14 KiB
Bash
Executable file
#!/bin/sh
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#
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# Copyright (c) 2008 Nicolas Pitre
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#
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test_description='resilience to pack corruptions with redundant objects'
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. ./test-lib.sh
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# Note: the test objects are created with knowledge of their pack encoding
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# to ensure good code path coverage, and to facilitate direct alteration
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# later on. The assumed characteristics are:
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#
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# 1) blob_2 is a delta with blob_1 for base and blob_3 is a delta with blob2
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# for base, such that blob_3 delta depth is 2;
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#
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# 2) the bulk of object data is uncompressible so the text part remains
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# visible;
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#
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# 3) object header is always 2 bytes.
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create_test_files() {
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test-tool genrandom "foo" 2000 > file_1 &&
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test-tool genrandom "foo" 1800 > file_2 &&
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test-tool genrandom "foo" 1800 > file_3 &&
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echo " base " >> file_1 &&
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echo " delta1 " >> file_2 &&
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echo " delta delta2 " >> file_3 &&
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test-tool genrandom "bar" 150 >> file_2 &&
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test-tool genrandom "baz" 100 >> file_3
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}
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create_new_pack() {
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rm -rf .git &&
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git init &&
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blob_1=$(git hash-object -t blob -w file_1) &&
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blob_2=$(git hash-object -t blob -w file_2) &&
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blob_3=$(git hash-object -t blob -w file_3) &&
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pack=$(printf "$blob_1\n$blob_2\n$blob_3\n" |
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git pack-objects $@ .git/objects/pack/pack) &&
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pack=".git/objects/pack/pack-${pack}" &&
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git verify-pack -v ${pack}.pack
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}
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do_repack() {
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pack=$(printf "$blob_1\n$blob_2\n$blob_3\n" |
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git pack-objects $@ .git/objects/pack/pack) &&
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pack=".git/objects/pack/pack-${pack}"
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}
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do_corrupt_object() {
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ofs=$(git show-index < ${pack}.idx | grep $1 | cut -f1 -d" ") &&
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ofs=$(($ofs + $2)) &&
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chmod +w ${pack}.pack &&
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dd of=${pack}.pack bs=1 conv=notrunc seek=$ofs &&
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test_must_fail git verify-pack ${pack}.pack
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}
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printf '\0' > zero
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test_expect_success \
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'initial setup validation' \
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'create_test_files &&
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create_new_pack &&
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git prune-packed &&
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git cat-file blob $blob_1 > /dev/null &&
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git cat-file blob $blob_2 > /dev/null &&
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git cat-file blob $blob_3 > /dev/null'
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test_expect_success \
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'create corruption in header of first object' \
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'do_corrupt_object $blob_1 0 < zero &&
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test_must_fail git cat-file blob $blob_1 > /dev/null &&
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test_must_fail git cat-file blob $blob_2 > /dev/null &&
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test_must_fail git cat-file blob $blob_3 > /dev/null'
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test_expect_success \
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'... but having a loose copy allows for full recovery' \
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'mv ${pack}.idx tmp &&
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git hash-object -t blob -w file_1 &&
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mv tmp ${pack}.idx &&
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git cat-file blob $blob_1 > /dev/null &&
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git cat-file blob $blob_2 > /dev/null &&
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git cat-file blob $blob_3 > /dev/null'
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test_expect_success \
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'... and loose copy of first delta allows for partial recovery' \
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'git prune-packed &&
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test_must_fail git cat-file blob $blob_2 > /dev/null &&
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mv ${pack}.idx tmp &&
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git hash-object -t blob -w file_2 &&
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mv tmp ${pack}.idx &&
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test_must_fail git cat-file blob $blob_1 > /dev/null &&
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git cat-file blob $blob_2 > /dev/null &&
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git cat-file blob $blob_3 > /dev/null'
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test_expect_success \
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'create corruption in data of first object' \
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'create_new_pack &&
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git prune-packed &&
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chmod +w ${pack}.pack &&
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perl -i.bak -pe "s/ base /abcdef/" ${pack}.pack &&
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test_must_fail git cat-file blob $blob_1 > /dev/null &&
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test_must_fail git cat-file blob $blob_2 > /dev/null &&
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test_must_fail git cat-file blob $blob_3 > /dev/null'
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test_expect_success \
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'... but having a loose copy allows for full recovery' \
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'mv ${pack}.idx tmp &&
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git hash-object -t blob -w file_1 &&
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mv tmp ${pack}.idx &&
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git cat-file blob $blob_1 > /dev/null &&
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git cat-file blob $blob_2 > /dev/null &&
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git cat-file blob $blob_3 > /dev/null'
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test_expect_success \
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'... and loose copy of second object allows for partial recovery' \
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'git prune-packed &&
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test_must_fail git cat-file blob $blob_2 > /dev/null &&
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mv ${pack}.idx tmp &&
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git hash-object -t blob -w file_2 &&
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mv tmp ${pack}.idx &&
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test_must_fail git cat-file blob $blob_1 > /dev/null &&
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git cat-file blob $blob_2 > /dev/null &&
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git cat-file blob $blob_3 > /dev/null'
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test_expect_success \
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'create corruption in header of first delta' \
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'create_new_pack &&
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git prune-packed &&
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do_corrupt_object $blob_2 0 < zero &&
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git cat-file blob $blob_1 > /dev/null &&
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test_must_fail git cat-file blob $blob_2 > /dev/null &&
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test_must_fail git cat-file blob $blob_3 > /dev/null'
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test_expect_success \
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'... but having a loose copy allows for full recovery' \
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'mv ${pack}.idx tmp &&
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git hash-object -t blob -w file_2 &&
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mv tmp ${pack}.idx &&
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git cat-file blob $blob_1 > /dev/null &&
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git cat-file blob $blob_2 > /dev/null &&
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git cat-file blob $blob_3 > /dev/null'
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test_expect_success \
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'... and then a repack "clears" the corruption' \
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'do_repack &&
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git prune-packed &&
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git verify-pack ${pack}.pack &&
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git cat-file blob $blob_1 > /dev/null &&
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git cat-file blob $blob_2 > /dev/null &&
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git cat-file blob $blob_3 > /dev/null'
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test_expect_success \
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'create corruption in data of first delta' \
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'create_new_pack &&
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git prune-packed &&
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chmod +w ${pack}.pack &&
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perl -i.bak -pe "s/ delta1 /abcdefgh/" ${pack}.pack &&
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git cat-file blob $blob_1 > /dev/null &&
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test_must_fail git cat-file blob $blob_2 > /dev/null &&
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test_must_fail git cat-file blob $blob_3 > /dev/null'
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test_expect_success \
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'... but having a loose copy allows for full recovery' \
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'mv ${pack}.idx tmp &&
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git hash-object -t blob -w file_2 &&
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mv tmp ${pack}.idx &&
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git cat-file blob $blob_1 > /dev/null &&
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git cat-file blob $blob_2 > /dev/null &&
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git cat-file blob $blob_3 > /dev/null'
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test_expect_success \
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'... and then a repack "clears" the corruption' \
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'do_repack &&
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git prune-packed &&
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git verify-pack ${pack}.pack &&
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git cat-file blob $blob_1 > /dev/null &&
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git cat-file blob $blob_2 > /dev/null &&
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git cat-file blob $blob_3 > /dev/null'
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test_expect_success \
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'corruption in delta base reference of first delta (OBJ_REF_DELTA)' \
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'create_new_pack &&
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git prune-packed &&
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do_corrupt_object $blob_2 2 < zero &&
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git cat-file blob $blob_1 > /dev/null &&
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test_must_fail git cat-file blob $blob_2 > /dev/null &&
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test_must_fail git cat-file blob $blob_3 > /dev/null'
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test_expect_success \
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'... but having a loose copy allows for full recovery' \
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'mv ${pack}.idx tmp &&
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git hash-object -t blob -w file_2 &&
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mv tmp ${pack}.idx &&
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git cat-file blob $blob_1 > /dev/null &&
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git cat-file blob $blob_2 > /dev/null &&
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git cat-file blob $blob_3 > /dev/null'
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test_expect_success \
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'... and then a repack "clears" the corruption' \
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'do_repack &&
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git prune-packed &&
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git verify-pack ${pack}.pack &&
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git cat-file blob $blob_1 > /dev/null &&
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git cat-file blob $blob_2 > /dev/null &&
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git cat-file blob $blob_3 > /dev/null'
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test_expect_success \
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'corruption #0 in delta base reference of first delta (OBJ_OFS_DELTA)' \
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'create_new_pack --delta-base-offset &&
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git prune-packed &&
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do_corrupt_object $blob_2 2 < zero &&
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git cat-file blob $blob_1 > /dev/null &&
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test_must_fail git cat-file blob $blob_2 > /dev/null &&
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test_must_fail git cat-file blob $blob_3 > /dev/null'
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test_expect_success \
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'... but having a loose copy allows for full recovery' \
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'mv ${pack}.idx tmp &&
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git hash-object -t blob -w file_2 &&
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mv tmp ${pack}.idx &&
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git cat-file blob $blob_1 > /dev/null &&
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git cat-file blob $blob_2 > /dev/null &&
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git cat-file blob $blob_3 > /dev/null'
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test_expect_success \
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'... and then a repack "clears" the corruption' \
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'do_repack --delta-base-offset &&
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git prune-packed &&
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git verify-pack ${pack}.pack &&
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git cat-file blob $blob_1 > /dev/null &&
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git cat-file blob $blob_2 > /dev/null &&
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git cat-file blob $blob_3 > /dev/null'
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test_expect_success \
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'corruption #1 in delta base reference of first delta (OBJ_OFS_DELTA)' \
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'create_new_pack --delta-base-offset &&
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git prune-packed &&
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printf "\001" | do_corrupt_object $blob_2 2 &&
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git cat-file blob $blob_1 > /dev/null &&
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test_must_fail git cat-file blob $blob_2 > /dev/null &&
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test_must_fail git cat-file blob $blob_3 > /dev/null'
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test_expect_success \
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'... but having a loose copy allows for full recovery' \
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'mv ${pack}.idx tmp &&
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git hash-object -t blob -w file_2 &&
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mv tmp ${pack}.idx &&
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git cat-file blob $blob_1 > /dev/null &&
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git cat-file blob $blob_2 > /dev/null &&
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git cat-file blob $blob_3 > /dev/null'
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test_expect_success \
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'... and then a repack "clears" the corruption' \
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'do_repack --delta-base-offset &&
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git prune-packed &&
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git verify-pack ${pack}.pack &&
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git cat-file blob $blob_1 > /dev/null &&
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git cat-file blob $blob_2 > /dev/null &&
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git cat-file blob $blob_3 > /dev/null'
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test_expect_success \
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'... and a redundant pack allows for full recovery too' \
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'do_corrupt_object $blob_2 2 < zero &&
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git cat-file blob $blob_1 > /dev/null &&
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test_must_fail git cat-file blob $blob_2 > /dev/null &&
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test_must_fail git cat-file blob $blob_3 > /dev/null &&
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mv ${pack}.idx tmp &&
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git hash-object -t blob -w file_1 &&
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git hash-object -t blob -w file_2 &&
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printf "$blob_1\n$blob_2\n" | git pack-objects .git/objects/pack/pack &&
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git prune-packed &&
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mv tmp ${pack}.idx &&
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git cat-file blob $blob_1 > /dev/null &&
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git cat-file blob $blob_2 > /dev/null &&
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git cat-file blob $blob_3 > /dev/null'
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test_expect_success \
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'corruption of delta base reference pointing to wrong object' \
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'create_new_pack --delta-base-offset &&
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git prune-packed &&
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printf "\220\033" | do_corrupt_object $blob_3 2 &&
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git cat-file blob $blob_1 >/dev/null &&
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git cat-file blob $blob_2 >/dev/null &&
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test_must_fail git cat-file blob $blob_3 >/dev/null'
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test_expect_success \
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'... but having a loose copy allows for full recovery' \
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'mv ${pack}.idx tmp &&
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git hash-object -t blob -w file_3 &&
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mv tmp ${pack}.idx &&
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git cat-file blob $blob_1 > /dev/null &&
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git cat-file blob $blob_2 > /dev/null &&
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git cat-file blob $blob_3 > /dev/null'
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test_expect_success \
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'... and then a repack "clears" the corruption' \
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'do_repack --delta-base-offset --no-reuse-delta &&
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git prune-packed &&
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git verify-pack ${pack}.pack &&
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git cat-file blob $blob_1 > /dev/null &&
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git cat-file blob $blob_2 > /dev/null &&
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git cat-file blob $blob_3 > /dev/null'
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test_expect_success \
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'corrupting header to have too small output buffer fails unpack' \
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'create_new_pack &&
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git prune-packed &&
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printf "\262\001" | do_corrupt_object $blob_1 0 &&
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test_must_fail git cat-file blob $blob_1 > /dev/null &&
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test_must_fail git cat-file blob $blob_2 > /dev/null &&
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test_must_fail git cat-file blob $blob_3 > /dev/null'
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# \0 - empty base
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# \1 - one byte in result
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# \1 - one literal byte (X)
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test_expect_success \
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'apply good minimal delta' \
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'printf "\0\1\1X" > minimal_delta &&
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test-tool delta -p /dev/null minimal_delta /dev/null'
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# \0 - empty base
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# \1 - 1 byte in result
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# \2 - two literal bytes (one too many)
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test_expect_success \
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'apply delta with too many literal bytes' \
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'printf "\0\1\2XX" > too_big_literal &&
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test_must_fail test-tool delta -p /dev/null too_big_literal /dev/null'
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# \5 - five bytes in base
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# \1 - one byte in result
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# \221 - copy, one byte offset, one byte size
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# \0 - copy from offset 0
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# \2 - copy two bytes (one too many)
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test_expect_success \
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'apply delta with too many copied bytes' \
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'printf "\5\1\221\0\2" > too_big_copy &&
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echo base >base &&
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test_must_fail test-tool delta -p base too_big_copy /dev/null'
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# \0 - empty base
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# \2 - two bytes in result
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# \2 - two literal bytes (we are short one)
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test_expect_success \
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'apply delta with too few literal bytes' \
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'printf "\0\2\2X" > truncated_delta &&
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test_must_fail test-tool delta -p /dev/null truncated_delta /dev/null'
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# \0 - empty base
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# \1 - one byte in result
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# \221 - copy, one byte offset, one byte size
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# \0 - copy from offset 0
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# \1 - copy one byte (we are short one)
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test_expect_success \
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'apply delta with too few bytes in base' \
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'printf "\0\1\221\0\1" > truncated_base &&
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test_must_fail test-tool delta -p /dev/null truncated_base /dev/null'
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# \5 - five bytes in base
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# \5 - five bytes in result
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# \1 - one literal byte (X)
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# \221 - copy, one byte offset, one byte size
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# (offset/size missing)
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#
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# Note that the literal byte is necessary to get past the uninteresting minimum
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# delta size check.
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test_expect_success \
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'apply delta with truncated copy parameters' \
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'printf "\5\5\1X\221" > truncated_copy_delta &&
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echo base >base &&
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test_must_fail test-tool delta -p base truncated_copy_delta /dev/null'
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# \0 - empty base
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# \1 - one byte in result
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# \1 - one literal byte (X)
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# \1 - trailing garbage command
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test_expect_success \
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'apply delta with trailing garbage literal' \
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'printf "\0\1\1X\1" > tail_garbage_literal &&
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test_must_fail test-tool delta -p /dev/null tail_garbage_literal /dev/null'
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# \5 - five bytes in base
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# \1 - one byte in result
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# \1 - one literal byte (X)
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# \221 - copy, one byte offset, one byte size
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# \0 - copy from offset 0
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# \1 - copy 1 byte
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test_expect_success \
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'apply delta with trailing garbage copy' \
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'printf "\5\1\1X\221\0\1" > tail_garbage_copy &&
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echo base >base &&
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test_must_fail test-tool delta -p /dev/null tail_garbage_copy /dev/null'
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# \0 - empty base
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# \1 - one byte in result
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# \1 - one literal byte (X)
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# \0 - bogus opcode
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test_expect_success \
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'apply delta with trailing garbage opcode' \
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'printf "\0\1\1X\0" > tail_garbage_opcode &&
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test_must_fail test-tool delta -p /dev/null tail_garbage_opcode /dev/null'
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test_done
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