chore: import upstream snapshot with attribution

Sources/CShim/socket_helpers.c

@@ -0,0 +1,33 @@
+/*
+ * Copyright © 2025-2026 Apple Inc. and the Containerization project authors.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *   https://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#include "socket_helpers.h"
+
+struct cmsghdr* CZ_CMSG_FIRSTHDR(struct msghdr *msg) {
+    return CMSG_FIRSTHDR(msg);
+}
+
+void* CZ_CMSG_DATA(struct cmsghdr *cmsg) {
+    return CMSG_DATA(cmsg);
+}
+
+size_t CZ_CMSG_SPACE(size_t length) {
+    return CMSG_SPACE(length);
+}
+
+size_t CZ_CMSG_LEN(size_t length) {
+    return CMSG_LEN(length);
+}