1 /*
2  * Copyright (C) 2019 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 #define TRACE_TAG FDEVENT
18 
19 #include "sysdeps.h"
20 #include "fdevent_poll.h"
21 
22 #include <fcntl.h>
23 #include <inttypes.h>
24 #include <stdint.h>
25 #include <stdlib.h>
26 #include <string.h>
27 #include <unistd.h>
28 
29 #include <atomic>
30 #include <deque>
31 #include <functional>
32 #include <list>
33 #include <mutex>
34 #include <optional>
35 #include <unordered_map>
36 #include <utility>
37 #include <variant>
38 #include <vector>
39 
40 #include <android-base/chrono_utils.h>
41 #include <android-base/file.h>
42 #include <android-base/logging.h>
43 #include <android-base/stringprintf.h>
44 #include <android-base/threads.h>
45 
46 #include "adb_io.h"
47 #include "adb_trace.h"
48 #include "adb_unique_fd.h"
49 #include "adb_utils.h"
50 #include "fdevent.h"
51 #include "sysdeps/chrono.h"
52 
53 static void fdevent_interrupt(int fd, unsigned, void*) {
54     char buf[BUFSIZ];
55     ssize_t rc = TEMP_FAILURE_RETRY(adb_read(fd, buf, sizeof(buf)));
56     if (rc == -1) {
57         PLOG(FATAL) << "failed to read from fdevent interrupt fd";
58     }
59 }
60 
61 fdevent_context_poll::fdevent_context_poll() {
62     int s[2];
63     if (adb_socketpair(s) != 0) {
64         PLOG(FATAL) << "failed to create fdevent interrupt socketpair";
65     }
66 
67     if (!set_file_block_mode(s[0], false) || !set_file_block_mode(s[1], false)) {
68         PLOG(FATAL) << "failed to make fdevent interrupt socket nonblocking";
69     }
70 
71     this->interrupt_fd_.reset(s[0]);
72     fdevent* fde = this->Create(unique_fd(s[1]), fdevent_interrupt, nullptr);
73     CHECK(fde != nullptr);
74     this->Add(fde, FDE_READ);
75 }
76 
77 fdevent_context_poll::~fdevent_context_poll() {
78     // Destroy calls virtual methods, but this class is final, so that's okay.
79     this->Destroy(this->interrupt_fde_);
80 }
81 
82 void fdevent_context_poll::Set(fdevent* fde, unsigned events) {
83     CheckMainThread();
84     fde->state = events;
85     D("fdevent_set: %s, events = %u", dump_fde(fde).c_str(), events);
86 }
87 
88 static std::string dump_pollfds(const std::vector<adb_pollfd>& pollfds) {
89     std::string result;
90     for (const auto& pollfd : pollfds) {
91         std::string op;
92         if (pollfd.events & POLLIN) {
93             op += "R";
94         }
95         if (pollfd.events & POLLOUT) {
96             op += "W";
97         }
98         android::base::StringAppendF(&result, " %d(%s)", pollfd.fd, op.c_str());
99     }
100     return result;
101 }
102 
103 void fdevent_context_poll::Loop() {
104     main_thread_id_ = android::base::GetThreadId();
105 
106     std::vector<adb_pollfd> pollfds;
107     std::vector<fdevent_event> poll_events;
108 
109     while (true) {
110         if (terminate_loop_) {
111             break;
112         }
113 
114         D("--- --- waiting for events");
115         pollfds.clear();
116         for (const auto& [fd, fde] : this->installed_fdevents_) {
117             adb_pollfd pfd;
118             pfd.fd = fd;
119             pfd.events = 0;
120             if (fde.state & FDE_READ) {
121                 pfd.events |= POLLIN;
122             }
123             if (fde.state & FDE_WRITE) {
124                 pfd.events |= POLLOUT;
125             }
126             if (fde.state & FDE_ERROR) {
127                 pfd.events |= POLLERR;
128             }
129 #if defined(__linux__)
130             pfd.events |= POLLRDHUP;
131 #endif
132             pfd.revents = 0;
133             pollfds.push_back(pfd);
134         }
135         CHECK_GT(pollfds.size(), 0u);
136         D("poll(), pollfds = %s", dump_pollfds(pollfds).c_str());
137 
138         std::optional<std::chrono::milliseconds> timeout = CalculatePollDuration();
139         int timeout_ms;
140         if (!timeout) {
141             timeout_ms = -1;
142         } else {
143             timeout_ms = timeout->count();
144         }
145 
146         int ret = adb_poll(pollfds.data(), pollfds.size(), timeout_ms);
147         if (ret == -1) {
148             PLOG(ERROR) << "poll(), ret = " << ret;
149             return;
150         }
151 
152         auto post_poll = std::chrono::steady_clock::now();
153 
154         for (const auto& pollfd : pollfds) {
155             unsigned events = 0;
156             if (pollfd.revents & POLLIN) {
157                 events |= FDE_READ;
158             }
159             if (pollfd.revents & POLLOUT) {
160                 events |= FDE_WRITE;
161             }
162             if (pollfd.revents & (POLLERR | POLLHUP | POLLNVAL)) {
163                 // We fake a read, as the rest of the code assumes that errors will
164                 // be detected at that point.
165                 events |= FDE_READ | FDE_ERROR;
166             }
167 #if defined(__linux__)
168             if (pollfd.revents & POLLRDHUP) {
169                 events |= FDE_READ | FDE_ERROR;
170             }
171 #endif
172 
173             auto it = this->installed_fdevents_.find(pollfd.fd);
174             CHECK(it != this->installed_fdevents_.end());
175             fdevent* fde = &it->second;
176 
177             if (events == 0) {
178                 if (fde->timeout) {
179                     auto deadline = fde->last_active + *fde->timeout;
180                     if (deadline < post_poll) {
181                         events |= FDE_TIMEOUT;
182                     }
183                 }
184             }
185 
186             if (events != 0) {
187                 D("%s got events %x", dump_fde(fde).c_str(), events);
188                 poll_events.push_back({fde, events});
189                 fde->last_active = post_poll;
190             }
191         }
192         this->HandleEvents(poll_events);
193         poll_events.clear();
194     }
195 
196     main_thread_id_.reset();
197 }
198 
199 size_t fdevent_context_poll::InstalledCount() {
200     // We always have an installed fde for interrupt.
201     return this->installed_fdevents_.size() - 1;
202 }
203 
204 void fdevent_context_poll::Interrupt() {
205     int rc = adb_write(this->interrupt_fd_, "", 1);
206 
207     // It's possible that we get EAGAIN here, if lots of notifications came in while handling.
208     if (rc == 0) {
209         PLOG(FATAL) << "fdevent interrupt fd was closed?";
210     } else if (rc == -1 && errno != EAGAIN) {
211         PLOG(FATAL) << "failed to write to fdevent interrupt fd";
212     }
213 }
214 
215 void fdevent_context_poll::Register(fdevent*) {}
216 
217 void fdevent_context_poll::Unregister(fdevent*) {}
218