git/t/t5312-prune-corruption.sh

#!/bin/sh

test_description='
Test pruning of repositories with minor corruptions. The goal
here is that we should always be erring on the side of safety. So
if we see, for example, a ref with a bogus name, it is OK either to
bail out or to proceed using it as a reachable tip, but it is _not_
OK to proceed as if it did not exist. Otherwise we might silently
delete objects that cannot be recovered.

Note that we do assert command failure in these cases, because that is
what currently happens. If that changes, these tests should be revisited.
'
GIT_TEST_DEFAULT_INITIAL_BRANCH_NAME=main
export GIT_TEST_DEFAULT_INITIAL_BRANCH_NAME

. ./test-lib.sh

test_expect_success 'disable reflogs' '
	git config core.logallrefupdates false &&
	git reflog expire --expire=all --all
'

create_bogus_ref () {
	test_when_finished 'rm -f .git/refs/heads/bogus..name' &&
	echo $bogus >.git/refs/heads/bogus..name
}

test_expect_success 'create history reachable only from a bogus-named ref' '
	test_tick && git commit --allow-empty -m main &&
	base=$(git rev-parse HEAD) &&
	test_tick && git commit --allow-empty -m bogus &&
	bogus=$(git rev-parse HEAD) &&
	git cat-file commit $bogus >saved &&
	git reset --hard HEAD^
'

test_expect_success 'pruning does not drop bogus object' '
	test_when_finished "git hash-object -w -t commit saved" &&
	create_bogus_ref &&
	test_must_fail git prune --expire=now &&
	git cat-file -e $bogus
'

test_expect_success 'put bogus object into pack' '
	git tag reachable $bogus &&
	git repack -ad &&
	git tag -d reachable &&
	git cat-file -e $bogus
'

test_expect_success 'non-destructive repack ignores bogus name' '
	create_bogus_ref &&
	git repack -adk
'

test_expect_success 'destructive repack keeps packed object' '
	create_bogus_ref &&
	test_must_fail git repack -Ad --unpack-unreachable=now &&
	git cat-file -e $bogus &&
	test_must_fail git repack -ad &&
	git cat-file -e $bogus
'

# We create two new objects here, "one" and "two". Our
# main branch points to "two", which is deleted,
# corrupting the repository. But we'd like to make sure
# that the otherwise unreachable "one" is not pruned
# (since it is the user's best bet for recovering
# from the corruption).
#
# Note that we also point HEAD somewhere besides "two",
# as we want to make sure we test the case where we
# pick up the reference to "two" by iterating the refs,
# not by resolving HEAD.
test_expect_success 'create history with missing tip commit' '
	test_tick && git commit --allow-empty -m one &&
	recoverable=$(git rev-parse HEAD) &&
	git cat-file commit $recoverable >saved &&
	test_tick && git commit --allow-empty -m two &&
	missing=$(git rev-parse HEAD) &&
	git checkout --detach $base &&
	rm .git/objects/$(echo $missing | sed "s,..,&/,") &&
	test_must_fail git cat-file -e $missing
'

test_expect_success 'pruning with a corrupted tip does not drop history' '
	test_when_finished "git hash-object -w -t commit saved" &&
	test_must_fail git prune --expire=now &&
	git cat-file -e $recoverable
'

test_expect_success 'pack-refs does not silently delete broken loose ref' '
	git pack-refs --all --prune &&
	echo $missing >expect &&
	git rev-parse refs/heads/main >actual &&
	test_cmp expect actual
'

# we do not want to count on running pack-refs to
# actually pack it, as it is perfectly reasonable to
# skip processing a broken ref
test_expect_success 'create packed-refs file with broken ref' '
	rm -f .git/refs/heads/main &&
	cat >.git/packed-refs <<-EOF &&
	$missing refs/heads/main
	$recoverable refs/heads/other
	EOF
	echo $missing >expect &&
	git rev-parse refs/heads/main >actual &&
	test_cmp expect actual
'

test_expect_success 'pack-refs does not silently delete broken packed ref' '
	git pack-refs --all --prune &&
	git rev-parse refs/heads/main >actual &&
	test_cmp expect actual
'

test_expect_success 'pack-refs does not drop broken refs during deletion' '
	git update-ref -d refs/heads/other &&
	git rev-parse refs/heads/main >actual &&
	test_cmp expect actual
'

test_done