Tom Cherry | ed506f7 | 2017-05-25 15:58:59 -0700 | [diff] [blame] | 1 | /* |
| 2 | * Copyright (C) 2017 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 "uevent_listener.h" |
| 18 | |
| 19 | #include <fcntl.h> |
| 20 | #include <poll.h> |
| 21 | #include <string.h> |
| 22 | #include <unistd.h> |
| 23 | |
| 24 | #include <memory> |
| 25 | |
| 26 | #include <android-base/logging.h> |
| 27 | #include <cutils/uevent.h> |
| 28 | |
| 29 | static void ParseEvent(const char* msg, Uevent* uevent) { |
| 30 | uevent->partition_num = -1; |
| 31 | uevent->major = -1; |
| 32 | uevent->minor = -1; |
| 33 | uevent->action.clear(); |
| 34 | uevent->path.clear(); |
| 35 | uevent->subsystem.clear(); |
| 36 | uevent->firmware.clear(); |
| 37 | uevent->partition_name.clear(); |
| 38 | uevent->device_name.clear(); |
| 39 | // currently ignoring SEQNUM |
| 40 | while (*msg) { |
| 41 | if (!strncmp(msg, "ACTION=", 7)) { |
| 42 | msg += 7; |
| 43 | uevent->action = msg; |
| 44 | } else if (!strncmp(msg, "DEVPATH=", 8)) { |
| 45 | msg += 8; |
| 46 | uevent->path = msg; |
| 47 | } else if (!strncmp(msg, "SUBSYSTEM=", 10)) { |
| 48 | msg += 10; |
| 49 | uevent->subsystem = msg; |
| 50 | } else if (!strncmp(msg, "FIRMWARE=", 9)) { |
| 51 | msg += 9; |
| 52 | uevent->firmware = msg; |
| 53 | } else if (!strncmp(msg, "MAJOR=", 6)) { |
| 54 | msg += 6; |
| 55 | uevent->major = atoi(msg); |
| 56 | } else if (!strncmp(msg, "MINOR=", 6)) { |
| 57 | msg += 6; |
| 58 | uevent->minor = atoi(msg); |
| 59 | } else if (!strncmp(msg, "PARTN=", 6)) { |
| 60 | msg += 6; |
| 61 | uevent->partition_num = atoi(msg); |
| 62 | } else if (!strncmp(msg, "PARTNAME=", 9)) { |
| 63 | msg += 9; |
| 64 | uevent->partition_name = msg; |
| 65 | } else if (!strncmp(msg, "DEVNAME=", 8)) { |
| 66 | msg += 8; |
| 67 | uevent->device_name = msg; |
| 68 | } |
| 69 | |
| 70 | // advance to after the next \0 |
| 71 | while (*msg++) |
| 72 | ; |
| 73 | } |
| 74 | |
| 75 | if (LOG_UEVENTS) { |
| 76 | LOG(INFO) << "event { '" << uevent->action << "', '" << uevent->path << "', '" |
| 77 | << uevent->subsystem << "', '" << uevent->firmware << "', " << uevent->major |
| 78 | << ", " << uevent->minor << " }"; |
| 79 | } |
| 80 | } |
| 81 | |
| 82 | UeventListener::UeventListener() { |
| 83 | // is 256K enough? udev uses 16MB! |
| 84 | device_fd_.reset(uevent_open_socket(256 * 1024, true)); |
| 85 | if (device_fd_ == -1) { |
| 86 | LOG(FATAL) << "Could not open uevent socket"; |
| 87 | } |
| 88 | |
| 89 | fcntl(device_fd_, F_SETFL, O_NONBLOCK); |
| 90 | } |
| 91 | |
| 92 | bool UeventListener::ReadUevent(Uevent* uevent) const { |
| 93 | char msg[UEVENT_MSG_LEN + 2]; |
| 94 | int n = uevent_kernel_multicast_recv(device_fd_, msg, UEVENT_MSG_LEN); |
| 95 | if (n <= 0) { |
| 96 | if (errno != EAGAIN && errno != EWOULDBLOCK) { |
| 97 | LOG(ERROR) << "Error reading from Uevent Fd"; |
| 98 | } |
| 99 | return false; |
| 100 | } |
| 101 | if (n >= UEVENT_MSG_LEN) { |
| 102 | LOG(ERROR) << "Uevent overflowed buffer, discarding"; |
| 103 | // Return true here even if we discard as we may have more uevents pending and we |
| 104 | // want to keep processing them. |
| 105 | return true; |
| 106 | } |
| 107 | |
| 108 | msg[n] = '\0'; |
| 109 | msg[n + 1] = '\0'; |
| 110 | |
| 111 | ParseEvent(msg, uevent); |
| 112 | |
| 113 | return true; |
| 114 | } |
| 115 | |
| 116 | // RegenerateUevents*() walks parts of the /sys tree and pokes the uevent files to cause the kernel |
| 117 | // to regenerate device add uevents that have already happened. This is particularly useful when |
| 118 | // starting ueventd, to regenerate all of the uevents that it had previously missed. |
| 119 | // |
| 120 | // We drain any pending events from the netlink socket every time we poke another uevent file to |
| 121 | // make sure we don't overrun the socket's buffer. |
| 122 | // |
| 123 | |
| 124 | RegenerationAction UeventListener::RegenerateUeventsForDir(DIR* d, |
| 125 | RegenerateCallback callback) const { |
| 126 | int dfd = dirfd(d); |
| 127 | |
| 128 | int fd = openat(dfd, "uevent", O_WRONLY); |
| 129 | if (fd >= 0) { |
| 130 | write(fd, "add\n", 4); |
| 131 | close(fd); |
| 132 | |
| 133 | Uevent uevent; |
| 134 | while (ReadUevent(&uevent)) { |
| 135 | if (callback(uevent) == RegenerationAction::kStop) return RegenerationAction::kStop; |
| 136 | } |
| 137 | } |
| 138 | |
| 139 | dirent* de; |
| 140 | while ((de = readdir(d)) != nullptr) { |
| 141 | if (de->d_type != DT_DIR || de->d_name[0] == '.') continue; |
| 142 | |
| 143 | fd = openat(dfd, de->d_name, O_RDONLY | O_DIRECTORY); |
| 144 | if (fd < 0) continue; |
| 145 | |
| 146 | std::unique_ptr<DIR, decltype(&closedir)> d2(fdopendir(fd), closedir); |
| 147 | if (d2 == 0) { |
| 148 | close(fd); |
| 149 | } else { |
| 150 | if (RegenerateUeventsForDir(d2.get(), callback) == RegenerationAction::kStop) { |
| 151 | return RegenerationAction::kStop; |
| 152 | } |
| 153 | } |
| 154 | } |
| 155 | |
| 156 | // default is always to continue looking for uevents |
| 157 | return RegenerationAction::kContinue; |
| 158 | } |
| 159 | |
| 160 | RegenerationAction UeventListener::RegenerateUeventsForPath(const std::string& path, |
| 161 | RegenerateCallback callback) const { |
| 162 | std::unique_ptr<DIR, decltype(&closedir)> d(opendir(path.c_str()), closedir); |
| 163 | if (!d) return RegenerationAction::kContinue; |
| 164 | |
| 165 | return RegenerateUeventsForDir(d.get(), callback); |
| 166 | } |
| 167 | |
Tom Cherry | d2fd54e | 2017-06-07 14:32:30 -0700 | [diff] [blame^] | 168 | static const char* kRegenerationPaths[] = {"/sys/class", "/sys/block", "/sys/devices"}; |
Tom Cherry | ed506f7 | 2017-05-25 15:58:59 -0700 | [diff] [blame] | 169 | |
| 170 | void UeventListener::RegenerateUevents(RegenerateCallback callback) const { |
| 171 | for (const auto path : kRegenerationPaths) { |
| 172 | if (RegenerateUeventsForPath(path, callback) == RegenerationAction::kStop) return; |
| 173 | } |
| 174 | } |
| 175 | |
| 176 | void UeventListener::DoPolling(PollCallback callback) const { |
| 177 | pollfd ufd; |
| 178 | ufd.events = POLLIN; |
| 179 | ufd.fd = device_fd_; |
| 180 | |
| 181 | while (true) { |
| 182 | ufd.revents = 0; |
| 183 | int nr = poll(&ufd, 1, -1); |
| 184 | if (nr <= 0) { |
| 185 | continue; |
| 186 | } |
| 187 | if (ufd.revents & POLLIN) { |
| 188 | // We're non-blocking, so if we receive a poll event keep processing until there |
| 189 | // we have exhausted all uevent messages. |
| 190 | Uevent uevent; |
| 191 | while (ReadUevent(&uevent)) { |
| 192 | callback(uevent); |
| 193 | } |
| 194 | } |
| 195 | } |
| 196 | } |