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1ee886c1f0
When we try to load an object from disk and fail, our general strategy is to see if we can get it from somewhere else (e.g., a loose object). That lets users fix corruption problems by copying known-good versions of objects into the object database. We already handle the case where we were not able to read the delta from disk. However, when we find that the delta we read does not apply, we simply die. This case is harder to trigger, as corruption in the delta data itself would trigger a crc error from zlib. However, a corruption that pointed us at the wrong delta base might cause it. We can do the same "fail and try to find the object elsewhere" trick instead of dying. This not only gives us a chance to recover, but also puts us on code paths that will alert the user to the problem (with the current message, they do not even know which sha1 caused the problem). Note that unlike some other pack corruptions, we do not recover automatically from this case when doing a repack. There is nothing apparently wrong with the delta, as it points to a valid, accessible object, and we realize the error only when the resulting size does not match up. And in theory, one could even have a case where the corrupted size is the same, and the problem would only be noticed by recomputing the sha1. We can get around this by recomputing the deltas with --no-reuse-delta, which our test does (and this is probably good advice for anyone recovering from pack corruption). Signed-off-by: Jeff King <peff@peff.net> Signed-off-by: Junio C Hamano <gitster@pobox.com>
314 lines
11 KiB
Bash
Executable file
314 lines
11 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-genrandom "foo" 2000 > file_1 &&
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test-genrandom "foo" 1800 > file_2 &&
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test-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-genrandom "bar" 150 >> file_2 &&
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test-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_PATH" -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_PATH" -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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test_done
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