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 #include <android-base/logging.h>
27
28 namespace android {
29 namespace init {
30
Epoll()31 Epoll::Epoll() {}
32
Open()33 Result<void> Epoll::Open() {
34 if (epoll_fd_ >= 0) return {};
35 epoll_fd_.reset(epoll_create1(EPOLL_CLOEXEC));
36
37 if (epoll_fd_ == -1) {
38 return ErrnoError() << "epoll_create1 failed";
39 }
40 return {};
41 }
42
RegisterHandler(int fd,Handler handler,uint32_t events)43 Result<void> Epoll::RegisterHandler(int fd, Handler handler, uint32_t events) {
44 if (!events) {
45 return Error() << "Must specify events";
46 }
47
48 auto [it, inserted] = epoll_handlers_.emplace(
49 fd, Info{
50 .events = events,
51 .handler = std::move(handler),
52 });
53 if (!inserted) {
54 return Error() << "Cannot specify two epoll handlers for a given FD";
55 }
56 epoll_event ev = {
57 .events = events,
58 .data.fd = fd,
59 };
60 if (epoll_ctl(epoll_fd_.get(), EPOLL_CTL_ADD, fd, &ev) == -1) {
61 Result<void> result = ErrnoError() << "epoll_ctl failed to add fd";
62 epoll_handlers_.erase(fd);
63 return result;
64 }
65 return {};
66 }
67
UnregisterHandler(int fd)68 Result<void> Epoll::UnregisterHandler(int fd) {
69 if (epoll_ctl(epoll_fd_.get(), EPOLL_CTL_DEL, fd, nullptr) == -1) {
70 return ErrnoError() << "epoll_ctl failed to remove fd";
71 }
72 auto it = epoll_handlers_.find(fd);
73 if (it == epoll_handlers_.end()) {
74 return Error() << "Attempting to remove epoll handler for FD without an existing handler";
75 }
76 to_remove_.insert(it->first);
77 return {};
78 }
79
SetFirstCallback(std::function<void ()> first_callback)80 void Epoll::SetFirstCallback(std::function<void()> first_callback) {
81 first_callback_ = std::move(first_callback);
82 }
83
Wait(std::optional<std::chrono::milliseconds> timeout)84 Result<int> Epoll::Wait(std::optional<std::chrono::milliseconds> timeout) {
85 int timeout_ms = -1;
86 if (timeout && timeout->count() < INT_MAX) {
87 timeout_ms = timeout->count();
88 }
89 const auto max_events = epoll_handlers_.size();
90 epoll_event ev[max_events];
91 auto num_events = TEMP_FAILURE_RETRY(epoll_wait(epoll_fd_.get(), ev, max_events, timeout_ms));
92 if (num_events == -1) {
93 return ErrnoError() << "epoll_wait failed";
94 }
95 if (num_events > 0 && first_callback_) {
96 first_callback_();
97 }
98 for (int i = 0; i < num_events; ++i) {
99 const auto it = epoll_handlers_.find(ev[i].data.fd);
100 if (it == epoll_handlers_.end()) {
101 continue;
102 }
103 const Info& info = it->second;
104 if ((info.events & (EPOLLIN | EPOLLPRI)) == (EPOLLIN | EPOLLPRI) &&
105 (ev[i].events & EPOLLIN) != ev[i].events) {
106 // This handler wants to know about exception events, and just got one.
107 // Log something informational.
108 LOG(ERROR) << "Received unexpected epoll event set: " << ev[i].events;
109 }
110 info.handler();
111 for (auto fd : to_remove_) {
112 epoll_handlers_.erase(fd);
113 }
114 to_remove_.clear();
115 }
116 return num_events;
117 }
118
119 } // namespace init
120 } // namespace android
121