init: Introduce class InterprocessFifo
Prepare for introducing a second interprocess communication channel by
introducing the class InterprocessFifo. Stop using std::unique_ptr<> for
holding the pipe file descriptors. Handle EOF consistently.
Bug: 213617178
Change-Id: Ic0cf18d3d8ea61b8ee17e64de8a9df2736e26728
Signed-off-by: Bart Van Assche <bvanassche@google.com>
diff --git a/init/interprocess_fifo.h b/init/interprocess_fifo.h
new file mode 100644
index 0000000..cdaac86
--- /dev/null
+++ b/init/interprocess_fifo.h
@@ -0,0 +1,52 @@
+/*
+ * Copyright (C) 2022 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 <array>
+
+#include <android-base/result.h>
+
+namespace android {
+namespace init {
+
+// A FIFO for inter-process communication that uses a Unix pipe internally.
+class InterprocessFifo {
+ public:
+ template <typename T>
+ using Result = ::android::base::Result<T>;
+
+ InterprocessFifo() noexcept;
+ InterprocessFifo(const InterprocessFifo& orig) noexcept = delete;
+ InterprocessFifo(InterprocessFifo&& orig) noexcept;
+ InterprocessFifo& operator=(const InterprocessFifo& orig) noexcept = delete;
+ InterprocessFifo& operator=(InterprocessFifo&& orig) noexcept = delete;
+ ~InterprocessFifo() noexcept;
+ void CloseReadFd() noexcept;
+ void CloseWriteFd() noexcept;
+ void Close() noexcept;
+ Result<void> Initialize() noexcept;
+ Result<void> Write(uint8_t byte) noexcept;
+ Result<uint8_t> Read() noexcept;
+
+ private:
+ static void CloseFd(int& fd) noexcept;
+
+ std::array<int, 2> fds_;
+};
+
+} // namespace init
+} // namespace android