Merge pull request libgit2#4105 from pks-t/pks/vector-reverse-overflow

Vector reverse overflow

Author: Edward Thomson

src/vector.c

@@ -406,6 +406,9 @@ void git_vector_reverse(git_vector *v)
 {
 	size_t a, b;
 
+	if (v->length == 0)
+		return;
+
 	a = 0;
 	b = v->length - 1;
 

tests/revwalk/basic.c

@@ -331,6 +331,20 @@ void test_revwalk_basic__hide_then_push(void)
 	cl_assert_equal_i(i, 0);
 }
 
+void test_revwalk_basic__topo_crash(void)
+{
+	git_oid oid;
+	git_oid_fromstr(&oid, "5b5b025afb0b4c913b4c338a42934a3863bf3644");
+
+	revwalk_basic_setup_walk(NULL);
+	git_revwalk_sorting(_walk, GIT_SORT_TOPOLOGICAL);
+
+	cl_git_pass(git_revwalk_push(_walk, &oid));
+	cl_git_pass(git_revwalk_hide(_walk, &oid));
+
+	git_revwalk_next(&oid, _walk);
+}
+
 void test_revwalk_basic__push_range(void)
 {
 	revwalk_basic_setup_walk(NULL);