Add new EpollController class.

The class is a thin wrapper for C epoll functions.

Bug: 34903085
Test: Build EpollController.cc and libappfuse_test after applying
      future changes locally.

Change-Id: Iedce7f35e4397f80cde1054d53261ad94f9e58a8

3 files changed, 117 insertions, 0 deletions

diff --git a/libappfuse/Android.bp b/libappfuse/Android.bp
index f729faf73..0d578144a 100644
--- a/libappfuse/Android.bp
+++ b/libappfuse/Android.bp
@@ -19,6 +19,7 @@ cc_library_shared {
         "FuseAppLoop.cc",
         "FuseBuffer.cc",
         "FuseBridgeLoop.cc",
+        "EpollController.cc",
     ]
 }
 
diff --git a/libappfuse/EpollController.cc b/libappfuse/EpollController.cc
new file mode 100644
index 000000000..9daeab8f4
--- /dev/null
+++ b/libappfuse/EpollController.cc
@@ -0,0 +1,66 @@
+/*
+ * 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 specic language governing permissions and
+ * limitations under the License.
+ */
+
+#include <android-base/logging.h>
+
+#include "libappfuse/EpollController.h"
+
+namespace android {
+namespace fuse {
+
+EpollController::EpollController(base::unique_fd&& poll_fd) : poll_fd_(std::move(poll_fd)) {
+}
+
+bool EpollController::Wait(size_t event_count) {
+    events_.resize(event_count);
+    const int result = TEMP_FAILURE_RETRY(epoll_wait(poll_fd_, events_.data(), event_count, -1));
+    if (result == -1) {
+        PLOG(ERROR) << "Failed to wait for epoll";
+        return false;
+    }
+    events_.resize(result);
+    return true;
+}
+
+bool EpollController::AddFd(int fd, int events, void* data) {
+    return InvokeControl(EPOLL_CTL_ADD, fd, events, data);
+}
+
+bool EpollController::UpdateFd(int fd, int events, void* data) {
+    return InvokeControl(EPOLL_CTL_MOD, fd, events, data);
+}
+
+bool EpollController::RemoveFd(int fd) {
+    return InvokeControl(EPOLL_CTL_DEL, fd, /* events */ 0, nullptr);
+}
+
+const std::vector<epoll_event>& EpollController::events() const {
+    return events_;
+}
+
+bool EpollController::InvokeControl(int op, int fd, int events, void* data) const {
+    epoll_event event;
+    memset(&event, 0, sizeof(event));
+    event.events = events;
+    event.data.ptr = data;
+    if (epoll_ctl(poll_fd_, op, fd, &event) == -1) {
+        PLOG(ERROR) << "epoll_ctl() error op=" << op;
+        return false;
+    }
+    return true;
+}
+}
+}
diff --git a/libappfuse/include/libappfuse/EpollController.h b/libappfuse/include/libappfuse/EpollController.h
new file mode 100644
index 000000000..3863abae7
--- /dev/null
+++ b/libappfuse/include/libappfuse/EpollController.h
@@ -0,0 +1,50 @@
+/*
+ * 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 specic language governing permissions and
+ * limitations under the License.
+ */
+
+#ifndef ANDROID_LIBAPPFUSE_EPOLLCONTROLLER_H_
+#define ANDROID_LIBAPPFUSE_EPOLLCONTROLLER_H_
+
+#include <sys/epoll.h>
+
+#include <vector>
+
+#include <android-base/macros.h>
+#include <android-base/unique_fd.h>
+
+namespace android {
+namespace fuse {
+
+class EpollController {
+  public:
+    explicit EpollController(base::unique_fd&& poll_fd);
+    bool Wait(size_t event_count);
+    bool AddFd(int fd, int events, void* data);
+    bool UpdateFd(int fd, int events, void* data);
+    bool RemoveFd(int fd);
+
+    const std::vector<epoll_event>& events() const;
+
+  private:
+    bool InvokeControl(int op, int fd, int events, void* data) const;
+    base::unique_fd poll_fd_;
+    std::vector<epoll_event> events_;
+
+    DISALLOW_COPY_AND_ASSIGN(EpollController);
+};
+}
+}
+
+#endif  // ANDROID_LIBAPPFUSE_EPOLLCONTROLLER_H_