Add utility classes (Slice, Fd, Status, etc)

Test: as follows
    - built
    - flashed
    - bootedt log
    - netdutils_test passes
    - unsubmitted NFLogListenerTest passes
Bug: 28806131

Change-Id: I17846a0dee1edca55df10e5464e607109d978cb5

1 files changed, 38 insertions, 0 deletions

diff --git a/libnetdutils/UniqueFd.cpp b/libnetdutils/UniqueFd.cpp
new file mode 100644
index 000000000..1cb30edde
--- /dev/null
+++ b/libnetdutils/UniqueFd.cpp
@@ -0,0 +1,38 @@
+/*
+ * Copyright (C) 2017 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.
+ */
+
+#include <algorithm>
+
+#include "netdutils/UniqueFd.h"
+#include "netdutils/Syscalls.h"
+
+namespace android {
+namespace netdutils {
+
+void UniqueFd::reset(Fd fd) {
+    auto& sys = sSyscalls.get();
+    std::swap(fd, mFd);
+    if (isWellFormed(fd)) {
+        expectOk(sys.close(fd));
+    }
+}
+
+std::ostream& operator<<(std::ostream& os, const UniqueFd& fd) {
+    return os << "UniqueFd[" << static_cast<Fd>(fd) << "]";
+}
+
+}  // namespace netdutils
+}  // namespace android