Commit b112b1e9adb6e90f77762aa2cb1eb376f709412f

Patrick Steinhardt 2017-10-06T11:24:11

refs: do not use peeled OID if peeling to a tag If a reference stored in a packed-refs file does not directly point to a commit, tree or blob, the packed-refs file will also will include a fully-peeled OID pointing to the first underlying object of that type. If we try to peel a reference to an object, we will use that peeled OID to speed up resolving the object. As a reference for an annotated tag does not directly point to a commit, tree or blob but instead to the tag object, the packed-refs file will have an accomodating fully-peeled OID pointing to the object referenced by that tag. When we use the fully-peeled OID pointing to the referenced object when peeling, we obviously cannot peel that to the tag anymore. Fix this issue by not using the fully-peeled OID whenever we want to peel to a tag. Note that this does not include the case where we want to resolve to _any_ object type. Existing code may make use from the fact that we resolve those to commit objects instead of tag objects, even though that behaviour is inconsistent between packed and loose references. Furthermore, some tests of ours make the assumption that we in fact resolve those references to a commit.

diff --git a/src/refs.c b/src/refs.c
index 9420540..550963e 100644
--- a/src/refs.c
+++ b/src/refs.c
@@ -1360,7 +1360,13 @@ int git_reference_peel(
 			return peel_error(error, ref, "Cannot resolve reference");
 	}
 
-	if (!git_oid_iszero(&resolved->peel)) {
+	/*
+	 * If we try to peel an object to a tag, we cannot use
+	 * the fully peeled object, as that will always resolve
+	 * to a commit. So we only want to use the peeled value
+	 * if it is not zero and the target is not a tag.
+	 */
+	if (target_type != GIT_OBJ_TAG && !git_oid_iszero(&resolved->peel)) {
 		error = git_object_lookup(&target,
 			git_reference_owner(ref), &resolved->peel, GIT_OBJ_ANY);
 	} else {
diff --git a/tests/refs/peel.c b/tests/refs/peel.c
index 83f6109..09809e1 100644
--- a/tests/refs/peel.c
+++ b/tests/refs/peel.c
@@ -117,3 +117,15 @@ void test_refs_peel__can_peel_fully_peeled_packed_refs(void)
 			    "0df1a5865c8abfc09f1f2182e6a31be550e99f07",
 			    GIT_OBJ_COMMIT);
 }
+
+void test_refs_peel__can_peel_fully_peeled_tag_to_tag(void)
+{
+	assert_peel_generic(g_peel_repo,
+			    "refs/tags/tag-inside-tags", GIT_OBJ_TAG,
+			    "c2596aa0151888587ec5c0187f261e63412d9e11",
+			    GIT_OBJ_TAG);
+	assert_peel_generic(g_peel_repo,
+			    "refs/foo/tag-outside-tags", GIT_OBJ_TAG,
+			    "c2596aa0151888587ec5c0187f261e63412d9e11",
+			    GIT_OBJ_TAG);
+}