1 /*
2 * Copyright (C) 2018 The Android Open Source Project
3 *
4 * Licensed under the Apache License, Version 2.0 (the "License");
5 * you may not use this file except in compliance with the License.
6 * You may obtain a copy of the License at
7 *
8 * http://www.apache.org/licenses/LICENSE-2.0
9 *
10 * Unless required by applicable law or agreed to in writing, software
11 * distributed under the License is distributed on an "AS IS" BASIS,
12 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
13 * See the License for the specific language governing permissions and
14 * limitations under the License.
15 */
16
17 #include "epoll.h"
18
19 #include <stdint.h>
20 #include <sys/epoll.h>
21
22 #include <chrono>
23 #include <functional>
24 #include <map>
25
26 namespace android {
27 namespace init {
28
Epoll()29 Epoll::Epoll() {}
30
Open()31 Result<Success> Epoll::Open() {
32 if (epoll_fd_ >= 0) return Success();
33 epoll_fd_.reset(epoll_create1(EPOLL_CLOEXEC));
34
35 if (epoll_fd_ == -1) {
36 return ErrnoError() << "epoll_create1 failed";
37 }
38 return Success();
39 }
40
RegisterHandler(int fd,std::function<void ()> handler,uint32_t events)41 Result<Success> Epoll::RegisterHandler(int fd, std::function<void()> handler, uint32_t events) {
42 if (!events) {
43 return Error() << "Must specify events";
44 }
45 auto [it, inserted] = epoll_handlers_.emplace(fd, std::move(handler));
46 if (!inserted) {
47 return Error() << "Cannot specify two epoll handlers for a given FD";
48 }
49 epoll_event ev;
50 ev.events = events;
51 // std::map's iterators do not get invalidated until erased, so we use the
52 // pointer to the std::function in the map directly for epoll_ctl.
53 ev.data.ptr = reinterpret_cast<void*>(&it->second);
54 if (epoll_ctl(epoll_fd_, EPOLL_CTL_ADD, fd, &ev) == -1) {
55 Result<Success> result = ErrnoError() << "epoll_ctl failed to add fd";
56 epoll_handlers_.erase(fd);
57 return result;
58 }
59 return Success();
60 }
61
UnregisterHandler(int fd)62 Result<Success> Epoll::UnregisterHandler(int fd) {
63 if (epoll_ctl(epoll_fd_, EPOLL_CTL_DEL, fd, nullptr) == -1) {
64 return ErrnoError() << "epoll_ctl failed to remove fd";
65 }
66 if (epoll_handlers_.erase(fd) != 1) {
67 return Error() << "Attempting to remove epoll handler for FD without an existing handler";
68 }
69 return Success();
70 }
71
Wait(std::optional<std::chrono::milliseconds> timeout)72 Result<Success> Epoll::Wait(std::optional<std::chrono::milliseconds> timeout) {
73 int timeout_ms = -1;
74 if (timeout && timeout->count() < INT_MAX) {
75 timeout_ms = timeout->count();
76 }
77 epoll_event ev;
78 auto nr = TEMP_FAILURE_RETRY(epoll_wait(epoll_fd_, &ev, 1, timeout_ms));
79 if (nr == -1) {
80 return ErrnoError() << "epoll_wait failed";
81 } else if (nr == 1) {
82 std::invoke(*reinterpret_cast<std::function<void()>*>(ev.data.ptr));
83 }
84 return Success();
85 }
86
87 } // namespace init
88 } // namespace android
89