git/t/t5326-multi-pack-bitmaps.sh
Derrick Stolee 756f1bcd29 fsck: verify checksums of all .bitmap files
If a filesystem-level corruption occurs in a .bitmap file, Git can react
poorly. This could take the form of a run-time error due to failing to
parse an EWAH bitmap or be more subtle such as returning the wrong set
of objects to a fetch or clone.

A natural first response to either of these kinds of errors is to run
'git fsck' to see if any files are corrupt. This currently ignores all
.bitmap files.

Add checks to 'git fsck' for all .bitmap files that are currently
associated with a multi-pack-index or pack file. Verify their checksums
using the hashfile API.

We iterate through all multi-pack-indexes and pack-files to be sure to
check all .bitmap files, not just the one that would be read by the
process. For example, a multi-pack-index bitmap overrules a pack-bitmap.
However, if the multi-pack-index is removed, the pack-bitmap may be
selected instead. Be thorough to include every file that could become
active in such a way. This includes checking files in alternates.

There is potential that we could extend this effort to check the
structure of the reachability bitmaps themselves, but it is very
expensive to do so. At minimum, it's as expensive as generating the
bitmaps in the first place, and that's assuming that we don't use the
trivial algorithm of verifying each bitmap individually. The trivial
algorithm will result in quadratic behavior (number of objects times
number of bitmapped commits) while the bitmap building operation
constructs a lattice of commits to build bitmaps incrementally and then
generate the final bitmaps from a subset of those commits.

If we were to extend 'git fsck' to check .bitmap file contents more
closely like this, then we would likely want to hide it behind an option
that signals the user is more willing to do expensive operations such as
this.

For testing, set up a repository with a pack-bitmap _and_ a
multi-pack-index bitmap. This requires some file movement to avoid
deleting the pack-bitmap during the repack that creates the
multi-pack-index bitmap. We can then verify that 'git fsck' is checking
all files, not just the "active" bitmap.

Signed-off-by: Derrick Stolee <derrickstolee@github.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2023-05-02 08:48:22 -07:00

481 lines
12 KiB
Bash
Executable file

#!/bin/sh
test_description='exercise basic multi-pack bitmap functionality'
. ./test-lib.sh
. "${TEST_DIRECTORY}/lib-bitmap.sh"
# We'll be writing our own midx and bitmaps, so avoid getting confused by the
# automatic ones.
GIT_TEST_MULTI_PACK_INDEX=0
GIT_TEST_MULTI_PACK_INDEX_WRITE_BITMAP=0
# This test exercise multi-pack bitmap functionality where the object order is
# stored and read from a special chunk within the MIDX, so use the default
# behavior here.
sane_unset GIT_TEST_MIDX_WRITE_REV
sane_unset GIT_TEST_MIDX_READ_RIDX
bitmap_reuse_tests() {
from=$1
to=$2
writeLookupTable=false
for i in $3-${$#}
do
case $i in
"pack.writeBitmapLookupTable") writeLookupTable=true;;
esac
done
test_expect_success "setup pack reuse tests ($from -> $to)" '
rm -fr repo &&
git init repo &&
(
cd repo &&
git config pack.writeBitmapLookupTable '"$writeLookupTable"' &&
test_commit_bulk 16 &&
git tag old-tip &&
git config core.multiPackIndex true &&
if test "MIDX" = "$from"
then
git repack -Ad &&
git multi-pack-index write --bitmap
else
git repack -Adb
fi
)
'
test_expect_success "build bitmap from existing ($from -> $to)" '
(
cd repo &&
git config pack.writeBitmapLookupTable '"$writeLookupTable"' &&
test_commit_bulk --id=further 16 &&
git tag new-tip &&
if test "MIDX" = "$to"
then
git repack -d &&
git multi-pack-index write --bitmap
else
git repack -Adb
fi
)
'
test_expect_success "verify resulting bitmaps ($from -> $to)" '
(
cd repo &&
git config pack.writeBitmapLookupTable '"$writeLookupTable"' &&
git for-each-ref &&
git rev-list --test-bitmap refs/tags/old-tip &&
git rev-list --test-bitmap refs/tags/new-tip
)
'
}
test_midx_bitmap_cases () {
writeLookupTable=false
writeBitmapLookupTable=
for i in "$@"
do
case $i in
"pack.writeBitmapLookupTable")
writeLookupTable=true
writeBitmapLookupTable="$i"
;;
esac
done
test_expect_success 'setup test_repository' '
rm -rf * .git &&
git init &&
git config pack.writeBitmapLookupTable '"$writeLookupTable"'
'
midx_bitmap_core
bitmap_reuse_tests 'pack' 'MIDX' "$writeBitmapLookupTable"
bitmap_reuse_tests 'MIDX' 'pack' "$writeBitmapLookupTable"
bitmap_reuse_tests 'MIDX' 'MIDX' "$writeBitmapLookupTable"
test_expect_success 'missing object closure fails gracefully' '
rm -fr repo &&
git init repo &&
test_when_finished "rm -fr repo" &&
(
cd repo &&
git config pack.writeBitmapLookupTable '"$writeLookupTable"' &&
test_commit loose &&
test_commit packed &&
# Do not pass "--revs"; we want a pack without the "loose"
# commit.
git pack-objects $objdir/pack/pack <<-EOF &&
$(git rev-parse packed)
EOF
test_must_fail git multi-pack-index write --bitmap 2>err &&
grep "doesn.t have full closure" err &&
test_path_is_missing $midx
)
'
midx_bitmap_partial_tests
test_expect_success 'removing a MIDX clears stale bitmaps' '
rm -fr repo &&
git init repo &&
test_when_finished "rm -fr repo" &&
(
cd repo &&
git config pack.writeBitmapLookupTable '"$writeLookupTable"' &&
test_commit base &&
git repack &&
git multi-pack-index write --bitmap &&
# Write a MIDX and bitmap; remove the MIDX but leave the bitmap.
stale_bitmap=$midx-$(midx_checksum $objdir).bitmap &&
rm $midx &&
# Then write a new MIDX.
test_commit new &&
git repack &&
git multi-pack-index write --bitmap &&
test_path_is_file $midx &&
test_path_is_file $midx-$(midx_checksum $objdir).bitmap &&
test_path_is_missing $stale_bitmap
)
'
test_expect_success 'pack.preferBitmapTips' '
git init repo &&
test_when_finished "rm -fr repo" &&
(
cd repo &&
git config pack.writeBitmapLookupTable '"$writeLookupTable"' &&
test_commit_bulk --message="%s" 103 &&
git log --format="%H" >commits.raw &&
sort <commits.raw >commits &&
git log --format="create refs/tags/%s %H" HEAD >refs &&
git update-ref --stdin <refs &&
git multi-pack-index write --bitmap &&
test_path_is_file $midx &&
test_path_is_file $midx-$(midx_checksum $objdir).bitmap &&
test-tool bitmap list-commits | sort >bitmaps &&
comm -13 bitmaps commits >before &&
test_line_count = 1 before &&
perl -ne "printf(\"create refs/tags/include/%d \", $.); print" \
<before | git update-ref --stdin &&
rm -fr $midx-$(midx_checksum $objdir).bitmap &&
rm -fr $midx &&
git -c pack.preferBitmapTips=refs/tags/include \
multi-pack-index write --bitmap &&
test-tool bitmap list-commits | sort >bitmaps &&
comm -13 bitmaps commits >after &&
! test_cmp before after
)
'
test_expect_success 'writing a bitmap with --refs-snapshot' '
git init repo &&
test_when_finished "rm -fr repo" &&
(
cd repo &&
git config pack.writeBitmapLookupTable '"$writeLookupTable"' &&
test_commit one &&
test_commit two &&
git rev-parse one >snapshot &&
git repack -ad &&
# First, write a MIDX which see both refs/tags/one and
# refs/tags/two (causing both of those commits to receive
# bitmaps).
git multi-pack-index write --bitmap &&
test_path_is_file $midx &&
test_path_is_file $midx-$(midx_checksum $objdir).bitmap &&
test-tool bitmap list-commits | sort >bitmaps &&
grep "$(git rev-parse one)" bitmaps &&
grep "$(git rev-parse two)" bitmaps &&
rm -fr $midx-$(midx_checksum $objdir).bitmap &&
rm -fr $midx &&
# Then again, but with a refs snapshot which only sees
# refs/tags/one.
git multi-pack-index write --bitmap --refs-snapshot=snapshot &&
test_path_is_file $midx &&
test_path_is_file $midx-$(midx_checksum $objdir).bitmap &&
test-tool bitmap list-commits | sort >bitmaps &&
grep "$(git rev-parse one)" bitmaps &&
! grep "$(git rev-parse two)" bitmaps
)
'
test_expect_success 'write a bitmap with --refs-snapshot (preferred tips)' '
git init repo &&
test_when_finished "rm -fr repo" &&
(
cd repo &&
git config pack.writeBitmapLookupTable '"$writeLookupTable"' &&
test_commit_bulk --message="%s" 103 &&
git log --format="%H" >commits.raw &&
sort <commits.raw >commits &&
git log --format="create refs/tags/%s %H" HEAD >refs &&
git update-ref --stdin <refs &&
git multi-pack-index write --bitmap &&
test_path_is_file $midx &&
test_path_is_file $midx-$(midx_checksum $objdir).bitmap &&
test-tool bitmap list-commits | sort >bitmaps &&
comm -13 bitmaps commits >before &&
test_line_count = 1 before &&
(
grep -vf before commits.raw &&
# mark missing commits as preferred
sed "s/^/+/" before
) >snapshot &&
rm -fr $midx-$(midx_checksum $objdir).bitmap &&
rm -fr $midx &&
git multi-pack-index write --bitmap --refs-snapshot=snapshot &&
test-tool bitmap list-commits | sort >bitmaps &&
comm -13 bitmaps commits >after &&
! test_cmp before after
)
'
test_expect_success 'hash-cache values are propagated from pack bitmaps' '
rm -fr repo &&
git init repo &&
test_when_finished "rm -fr repo" &&
(
cd repo &&
git config pack.writeBitmapLookupTable '"$writeLookupTable"' &&
test_commit base &&
test_commit base2 &&
git repack -adb &&
test-tool bitmap dump-hashes >pack.raw &&
test_file_not_empty pack.raw &&
sort pack.raw >pack.hashes &&
test_commit new &&
git repack &&
git multi-pack-index write --bitmap &&
test-tool bitmap dump-hashes >midx.raw &&
sort midx.raw >midx.hashes &&
# ensure that every namehash in the pack bitmap can be found in
# the midx bitmap (i.e., that there are no oid-namehash pairs
# unique to the pack bitmap).
comm -23 pack.hashes midx.hashes >dropped.hashes &&
test_must_be_empty dropped.hashes
)
'
test_expect_success 'no .bitmap is written without any objects' '
rm -fr repo &&
git init repo &&
test_when_finished "rm -fr repo" &&
(
cd repo &&
git config pack.writeBitmapLookupTable '"$writeLookupTable"' &&
empty="$(git pack-objects $objdir/pack/pack </dev/null)" &&
cat >packs <<-EOF &&
pack-$empty.idx
EOF
git multi-pack-index write --bitmap --stdin-packs \
<packs 2>err &&
grep "bitmap without any objects" err &&
test_path_is_file $midx &&
test_path_is_missing $midx-$(midx_checksum $objdir).bitmap
)
'
test_expect_success 'graceful fallback when missing reverse index' '
rm -fr repo &&
git init repo &&
test_when_finished "rm -fr repo" &&
(
cd repo &&
git config pack.writeBitmapLookupTable '"$writeLookupTable"' &&
test_commit base &&
# write a pack and MIDX bitmap containing base
git repack -adb &&
git multi-pack-index write --bitmap &&
GIT_TEST_MIDX_READ_RIDX=0 \
git rev-list --use-bitmap-index HEAD 2>err &&
! grep "ignoring extra bitmap file" err
)
'
}
test_midx_bitmap_cases
test_midx_bitmap_cases "pack.writeBitmapLookupTable"
test_expect_success 'multi-pack-index write writes lookup table if enabled' '
rm -fr repo &&
git init repo &&
test_when_finished "rm -fr repo" &&
(
cd repo &&
test_commit base &&
git config pack.writeBitmapLookupTable true &&
git repack -ad &&
GIT_TRACE2_EVENT="$(pwd)/trace" \
git multi-pack-index write --bitmap &&
grep "\"label\":\"writing_lookup_table\"" trace
)
'
test_expect_success 'preferred pack change with existing MIDX bitmap' '
git init preferred-pack-with-existing &&
(
cd preferred-pack-with-existing &&
test_commit base &&
test_commit other &&
git rev-list --objects --no-object-names base >p1.objects &&
git rev-list --objects --no-object-names other >p2.objects &&
p1="$(git pack-objects "$objdir/pack/pack" \
--delta-base-offset <p1.objects)" &&
p2="$(git pack-objects "$objdir/pack/pack" \
--delta-base-offset <p2.objects)" &&
# Generate a MIDX containing the first two packs,
# marking p1 as preferred, and ensure that it can be
# successfully cloned.
git multi-pack-index write --bitmap \
--preferred-pack="pack-$p1.pack" &&
test_path_is_file $midx &&
test_path_is_file $midx-$(midx_checksum $objdir).bitmap &&
git clone --no-local . clone1 &&
# Then generate a new pack which sorts ahead of any
# existing pack (by tweaking the pack prefix).
test_commit foo &&
git pack-objects --all --unpacked $objdir/pack/pack0 &&
# Generate a new MIDX which changes the preferred pack
# to a pack contained in the existing MIDX.
git multi-pack-index write --bitmap \
--preferred-pack="pack-$p2.pack" &&
test_path_is_file $midx &&
test_path_is_file $midx-$(midx_checksum $objdir).bitmap &&
# When the above circumstances are met, the preferred
# pack should change appropriately and clones should
# (still) succeed.
git clone --no-local . clone2
)
'
test_expect_success 'tagged commits are selected for bitmapping' '
rm -fr repo &&
git init repo &&
test_when_finished "rm -fr repo" &&
(
cd repo &&
test_commit --annotate base &&
git repack -d &&
# Remove refs/heads/main which points at the commit directly,
# leaving only a reference to the annotated tag.
git branch -M main &&
git checkout base &&
git branch -d main &&
git multi-pack-index write --bitmap &&
git rev-parse HEAD >want &&
test-tool bitmap list-commits >actual &&
grep $(cat want) actual
)
'
corrupt_file () {
chmod a+w "$1" &&
printf "bogus" | dd of="$1" bs=1 seek="12" conv=notrunc
}
test_expect_success 'git fsck correctly identifies good and bad bitmaps' '
git init valid &&
test_when_finished rm -rf valid &&
test_commit_bulk 20 &&
git repack -adbf &&
# Move pack-bitmap aside so it is not deleted
# in next repack.
packbitmap=$(ls .git/objects/pack/pack-*.bitmap) &&
mv "$packbitmap" "$packbitmap.bak" &&
test_commit_bulk 10 &&
git repack -b --write-midx &&
midxbitmap=$(ls .git/objects/pack/multi-pack-index-*.bitmap) &&
# Copy MIDX bitmap to backup. Copy pack bitmap from backup.
cp "$midxbitmap" "$midxbitmap.bak" &&
cp "$packbitmap.bak" "$packbitmap" &&
# fsck works at first
git fsck 2>err &&
test_must_be_empty err &&
corrupt_file "$packbitmap" &&
test_must_fail git fsck 2>err &&
grep "bitmap file '\''$packbitmap'\'' has invalid checksum" err &&
cp "$packbitmap.bak" "$packbitmap" &&
corrupt_file "$midxbitmap" &&
test_must_fail git fsck 2>err &&
grep "bitmap file '\''$midxbitmap'\'' has invalid checksum" err &&
corrupt_file "$packbitmap" &&
test_must_fail git fsck 2>err &&
grep "bitmap file '\''$midxbitmap'\'' has invalid checksum" err &&
grep "bitmap file '\''$packbitmap'\'' has invalid checksum" err
'
test_done