base: add helpers for sending/receiving file descriptors.
Almost all of the uses of cmsg(3) in our source tree are wrong in at
least one of the following ways:
- not aligning the cmsg buffer
- leaking fds if more fds are received than expected
- blindly dereferencing CMSG_DATA without checking the header
- using CMSG_SPACE instead of CMSG_LEN for .cmsg_len
- using CMSG_LEN instead of CMSG_SPACE for .msg_controllen
- using a length specified in number of fds instead of bytes
Implement wrapper functions that implement this dumpster fire of an
API correctly.
Bug: http://b/122047630
Test: libbase_test32
Change-Id: I6ac34d67bbbf1bfa9727ab598248fc178ea19df9
diff --git a/include/android-base/collections.h b/include/android-base/collections.h
new file mode 100644
index 0000000..be0683a
--- /dev/null
+++ b/include/android-base/collections.h
@@ -0,0 +1,60 @@
+/*
+ * Copyright (C) 2019 The Android Open Source Project
+ *
+ * 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
+ *
+ * http://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.
+ */
+
+#pragma once
+
+#include <utility>
+
+namespace android {
+namespace base {
+
+// Helpers for converting a variadic template parameter pack to a homogeneous collection.
+// Parameters must be implictly convertible to the contained type (including via move/copy ctors).
+//
+// Use as follows:
+//
+// template <typename... Args>
+// std::vector<int> CreateVector(Args&&... args) {
+// std::vector<int> result;
+// Append(result, std::forward<Args>(args)...);
+// return result;
+// }
+template <typename CollectionType, typename T>
+void Append(CollectionType& collection, T&& arg) {
+ collection.push_back(std::forward<T>(arg));
+}
+
+template <typename CollectionType, typename T, typename... Args>
+void Append(CollectionType& collection, T&& arg, Args&&... args) {
+ collection.push_back(std::forward<T>(arg));
+ return Append(collection, std::forward<Args>(args)...);
+}
+
+// Assert that all of the arguments in a variadic template parameter pack are of a given type
+// after std::decay.
+template <typename T, typename Arg, typename... Args>
+void AssertType(Arg&&) {
+ static_assert(std::is_same<T, typename std::decay<Arg>::type>::value);
+}
+
+template <typename T, typename Arg, typename... Args>
+void AssertType(Arg&&, Args&&... args) {
+ static_assert(std::is_same<T, typename std::decay<Arg>::type>::value);
+ AssertType<T>(std::forward<Args>(args)...);
+}
+
+} // namespace base
+} // namespace android