From 43f25158ca0ae31b663e37f6b538daf735df10a3 Mon Sep 17 00:00:00 2001
From: Jonathan Tan <jonathantanmy@google.com>
Date: Tue, 5 Dec 2017 16:58:45 +0000
Subject: [PATCH] fsck: support refs pointing to promisor objects

Teach fsck to not treat refs referring to missing promisor objects as an
error when extensions.partialclone is set.

For the purposes of warning about no default refs, such refs are still
treated as legitimate refs.

Signed-off-by: Jonathan Tan <jonathantanmy@google.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
---
 builtin/fsck.c           |  8 ++++++++
 t/t0410-partial-clone.sh | 24 ++++++++++++++++++++++++
 2 files changed, 32 insertions(+)

diff --git a/builtin/fsck.c b/builtin/fsck.c
index 29342998fd..ee937bbdbc 100644
--- a/builtin/fsck.c
+++ b/builtin/fsck.c
@@ -434,6 +434,14 @@ static int fsck_handle_ref(const char *refname, const struct object_id *oid,
 
 	obj = parse_object(oid);
 	if (!obj) {
+		if (is_promisor_object(oid)) {
+			/*
+			 * Increment default_refs anyway, because this is a
+			 * valid ref.
+			 */
+			 default_refs++;
+			 return 0;
+		}
 		error("%s: invalid sha1 pointer %s", refname, oid_to_hex(oid));
 		errors_found |= ERROR_REACHABLE;
 		/* We'll continue with the rest despite the error.. */
diff --git a/t/t0410-partial-clone.sh b/t/t0410-partial-clone.sh
index 3ddb3b98fe..bf75162c16 100755
--- a/t/t0410-partial-clone.sh
+++ b/t/t0410-partial-clone.sh
@@ -13,6 +13,14 @@ pack_as_from_promisor () {
 	>repo/.git/objects/pack/pack-$HASH.promisor
 }
 
+promise_and_delete () {
+	HASH=$(git -C repo rev-parse "$1") &&
+	git -C repo tag -a -m message my_annotated_tag "$HASH" &&
+	git -C repo rev-parse my_annotated_tag | pack_as_from_promisor &&
+	git -C repo tag -d my_annotated_tag &&
+	delete_object repo "$HASH"
+}
+
 test_expect_success 'missing reflog object, but promised by a commit, passes fsck' '
 	test_create_repo repo &&
 	test_commit -C repo my_commit &&
@@ -78,4 +86,20 @@ test_expect_success 'missing reflog object alone fails fsck, even with extension
 	test_must_fail git -C repo fsck
 '
 
+test_expect_success 'missing ref object, but promised, passes fsck' '
+	rm -rf repo &&
+	test_create_repo repo &&
+	test_commit -C repo my_commit &&
+
+	A=$(git -C repo commit-tree -m a HEAD^{tree}) &&
+
+	# Reference $A only from ref
+	git -C repo branch my_branch "$A" &&
+	promise_and_delete "$A" &&
+
+	git -C repo config core.repositoryformatversion 1 &&
+	git -C repo config extensions.partialclone "arbitrary string" &&
+	git -C repo fsck
+'
+
 test_done