refs/reftable: don't fail empty transactions in repo without HEAD

Under normal circumstances, it shouldn't ever happen that a repository
has no HEAD reference. In fact, git-update-ref(1) would fail any request
to delete the HEAD reference, and a newly initialized repository always
pre-creates it, too.

We have however changed git-clone(1) to partially initialize the
refdb just up to the point where remote helpers can find the
repository. With that change, we are going to run into a situation
where repositories have no refs at all.

Now there is a very particular edge case in this situation: when
preparing an empty ref transacton, we end up returning whatever value
`read_ref_without_reload()` returned to the caller. Under normal
conditions this would be fine: "HEAD" should usually exist, and thus the
function would return `0`. But if "HEAD" doesn't exist, the function
returns a positive value which we end up returning to the caller.

Fix this bug by resetting the return code to `0` and add a test.

Signed-off-by: Patrick Steinhardt <ps@pks.im>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
This commit is contained in:
Patrick Steinhardt 2024-02-27 15:27:39 +01:00 committed by Junio C Hamano
parent b6818ff3b1
commit b0f6b6b523
2 changed files with 14 additions and 0 deletions

View file

@ -821,6 +821,7 @@ static int reftable_be_transaction_prepare(struct ref_store *ref_store,
&head_referent, &head_type);
if (ret < 0)
goto done;
ret = 0;
for (i = 0; i < transaction->nr; i++) {
struct ref_update *u = transaction->updates[i];

View file

@ -328,6 +328,19 @@ test_expect_success 'ref transaction: writes are synced' '
EOF
'
test_expect_success 'ref transaction: empty transaction in empty repo' '
test_when_finished "rm -rf repo" &&
git init repo &&
test_commit -C repo --no-tag A &&
COMMIT=$(git -C repo rev-parse HEAD) &&
git -C repo update-ref -d refs/heads/main &&
test-tool -C repo ref-store main delete-refs REF_NO_DEREF msg HEAD &&
git -C repo update-ref --stdin <<-EOF
prepare
commit
EOF
'
test_expect_success 'pack-refs: compacts tables' '
test_when_finished "rm -rf repo" &&
git init repo &&