1 //===-- Communication.cpp -------------------------------------------------===// 2 // 3 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions. 4 // See https://llvm.org/LICENSE.txt for license information. 5 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception 6 // 7 //===----------------------------------------------------------------------===// 8 9 #include "lldb/Core/Communication.h" 10 11 #include "lldb/Host/HostThread.h" 12 #include "lldb/Host/ThreadLauncher.h" 13 #include "lldb/Utility/Connection.h" 14 #include "lldb/Utility/ConstString.h" 15 #include "lldb/Utility/Event.h" 16 #include "lldb/Utility/Listener.h" 17 #include "lldb/Utility/Log.h" 18 #include "lldb/Utility/Logging.h" 19 #include "lldb/Utility/Status.h" 20 21 #include "llvm/ADT/None.h" 22 #include "llvm/ADT/Optional.h" 23 #include "llvm/Support/Compiler.h" 24 25 #include <algorithm> 26 #include <chrono> 27 #include <cstring> 28 #include <memory> 29 30 #include <errno.h> 31 #include <inttypes.h> 32 #include <stdio.h> 33 34 using namespace lldb; 35 using namespace lldb_private; 36 37 ConstString &Communication::GetStaticBroadcasterClass() { 38 static ConstString class_name("lldb.communication"); 39 return class_name; 40 } 41 42 Communication::Communication(const char *name) 43 : Broadcaster(nullptr, name), m_connection_sp(), 44 m_read_thread_enabled(false), m_read_thread_did_exit(false), m_bytes(), 45 m_bytes_mutex(), m_write_mutex(), m_synchronize_mutex(), 46 m_callback(nullptr), m_callback_baton(nullptr), m_close_on_eof(true) 47 48 { 49 50 LLDB_LOG(lldb_private::GetLogIfAnyCategoriesSet(LIBLLDB_LOG_OBJECT | 51 LIBLLDB_LOG_COMMUNICATION), 52 "{0} Communication::Communication (name = {1})", this, name); 53 54 SetEventName(eBroadcastBitDisconnected, "disconnected"); 55 SetEventName(eBroadcastBitReadThreadGotBytes, "got bytes"); 56 SetEventName(eBroadcastBitReadThreadDidExit, "read thread did exit"); 57 SetEventName(eBroadcastBitReadThreadShouldExit, "read thread should exit"); 58 SetEventName(eBroadcastBitPacketAvailable, "packet available"); 59 SetEventName(eBroadcastBitNoMorePendingInput, "no more pending input"); 60 61 CheckInWithManager(); 62 } 63 64 Communication::~Communication() { 65 LLDB_LOG(lldb_private::GetLogIfAnyCategoriesSet(LIBLLDB_LOG_OBJECT | 66 LIBLLDB_LOG_COMMUNICATION), 67 "{0} Communication::~Communication (name = {1})", this, 68 GetBroadcasterName().AsCString()); 69 Clear(); 70 } 71 72 void Communication::Clear() { 73 SetReadThreadBytesReceivedCallback(nullptr, nullptr); 74 StopReadThread(nullptr); 75 Disconnect(nullptr); 76 } 77 78 ConnectionStatus Communication::Connect(const char *url, Status *error_ptr) { 79 Clear(); 80 81 LLDB_LOG(lldb_private::GetLogIfAllCategoriesSet(LIBLLDB_LOG_COMMUNICATION), 82 "{0} Communication::Connect (url = {1})", this, url); 83 84 lldb::ConnectionSP connection_sp(m_connection_sp); 85 if (connection_sp) 86 return connection_sp->Connect(url, error_ptr); 87 if (error_ptr) 88 error_ptr->SetErrorString("Invalid connection."); 89 return eConnectionStatusNoConnection; 90 } 91 92 ConnectionStatus Communication::Disconnect(Status *error_ptr) { 93 LLDB_LOG(lldb_private::GetLogIfAllCategoriesSet(LIBLLDB_LOG_COMMUNICATION), 94 "{0} Communication::Disconnect ()", this); 95 96 assert((!m_read_thread_enabled || m_read_thread_did_exit) && 97 "Disconnecting while the read thread is running is racy!"); 98 lldb::ConnectionSP connection_sp(m_connection_sp); 99 if (connection_sp) { 100 ConnectionStatus status = connection_sp->Disconnect(error_ptr); 101 // We currently don't protect connection_sp with any mutex for multi- 102 // threaded environments. So lets not nuke our connection class without 103 // putting some multi-threaded protections in. We also probably don't want 104 // to pay for the overhead it might cause if every time we access the 105 // connection we have to take a lock. 106 // 107 // This unique pointer will cleanup after itself when this object goes 108 // away, so there is no need to currently have it destroy itself 109 // immediately upon disconnect. 110 // connection_sp.reset(); 111 return status; 112 } 113 return eConnectionStatusNoConnection; 114 } 115 116 bool Communication::IsConnected() const { 117 lldb::ConnectionSP connection_sp(m_connection_sp); 118 return (connection_sp ? connection_sp->IsConnected() : false); 119 } 120 121 bool Communication::HasConnection() const { 122 return m_connection_sp.get() != nullptr; 123 } 124 125 size_t Communication::Read(void *dst, size_t dst_len, 126 const Timeout<std::micro> &timeout, 127 ConnectionStatus &status, Status *error_ptr) { 128 Log *log = GetLogIfAllCategoriesSet(LIBLLDB_LOG_COMMUNICATION); 129 LLDB_LOG( 130 log, 131 "this = {0}, dst = {1}, dst_len = {2}, timeout = {3}, connection = {4}", 132 this, dst, dst_len, timeout, m_connection_sp.get()); 133 134 if (m_read_thread_enabled) { 135 // We have a dedicated read thread that is getting data for us 136 size_t cached_bytes = GetCachedBytes(dst, dst_len); 137 if (cached_bytes > 0 || (timeout && timeout->count() == 0)) { 138 status = eConnectionStatusSuccess; 139 return cached_bytes; 140 } 141 142 if (!m_connection_sp) { 143 if (error_ptr) 144 error_ptr->SetErrorString("Invalid connection."); 145 status = eConnectionStatusNoConnection; 146 return 0; 147 } 148 149 ListenerSP listener_sp(Listener::MakeListener("Communication::Read")); 150 listener_sp->StartListeningForEvents( 151 this, eBroadcastBitReadThreadGotBytes | eBroadcastBitReadThreadDidExit); 152 EventSP event_sp; 153 while (listener_sp->GetEvent(event_sp, timeout)) { 154 const uint32_t event_type = event_sp->GetType(); 155 if (event_type & eBroadcastBitReadThreadGotBytes) { 156 return GetCachedBytes(dst, dst_len); 157 } 158 159 if (event_type & eBroadcastBitReadThreadDidExit) { 160 if (GetCloseOnEOF()) 161 Disconnect(nullptr); 162 break; 163 } 164 } 165 return 0; 166 } 167 168 // We aren't using a read thread, just read the data synchronously in this 169 // thread. 170 return ReadFromConnection(dst, dst_len, timeout, status, error_ptr); 171 } 172 173 size_t Communication::Write(const void *src, size_t src_len, 174 ConnectionStatus &status, Status *error_ptr) { 175 lldb::ConnectionSP connection_sp(m_connection_sp); 176 177 std::lock_guard<std::mutex> guard(m_write_mutex); 178 LLDB_LOG(lldb_private::GetLogIfAllCategoriesSet(LIBLLDB_LOG_COMMUNICATION), 179 "{0} Communication::Write (src = {1}, src_len = %" PRIu64 180 ") connection = {2}", 181 this, src, (uint64_t)src_len, connection_sp.get()); 182 183 if (connection_sp) 184 return connection_sp->Write(src, src_len, status, error_ptr); 185 186 if (error_ptr) 187 error_ptr->SetErrorString("Invalid connection."); 188 status = eConnectionStatusNoConnection; 189 return 0; 190 } 191 192 bool Communication::StartReadThread(Status *error_ptr) { 193 if (error_ptr) 194 error_ptr->Clear(); 195 196 if (m_read_thread.IsJoinable()) 197 return true; 198 199 LLDB_LOG(lldb_private::GetLogIfAllCategoriesSet(LIBLLDB_LOG_COMMUNICATION), 200 "{0} Communication::StartReadThread ()", this); 201 202 const std::string thread_name = 203 llvm::formatv("<lldb.comm.{0}>", GetBroadcasterName()); 204 205 m_read_thread_enabled = true; 206 m_read_thread_did_exit = false; 207 auto maybe_thread = ThreadLauncher::LaunchThread( 208 thread_name, Communication::ReadThread, this); 209 if (maybe_thread) { 210 m_read_thread = *maybe_thread; 211 } else { 212 if (error_ptr) 213 *error_ptr = Status(maybe_thread.takeError()); 214 else { 215 LLDB_LOG(lldb_private::GetLogIfAllCategoriesSet(LIBLLDB_LOG_HOST), 216 "failed to launch host thread: {}", 217 llvm::toString(maybe_thread.takeError())); 218 } 219 } 220 221 if (!m_read_thread.IsJoinable()) 222 m_read_thread_enabled = false; 223 224 return m_read_thread_enabled; 225 } 226 227 bool Communication::StopReadThread(Status *error_ptr) { 228 if (!m_read_thread.IsJoinable()) 229 return true; 230 231 LLDB_LOG(lldb_private::GetLogIfAllCategoriesSet(LIBLLDB_LOG_COMMUNICATION), 232 "{0} Communication::StopReadThread ()", this); 233 234 m_read_thread_enabled = false; 235 236 BroadcastEvent(eBroadcastBitReadThreadShouldExit, nullptr); 237 238 // error = m_read_thread.Cancel(); 239 240 Status error = m_read_thread.Join(nullptr); 241 return error.Success(); 242 } 243 244 bool Communication::JoinReadThread(Status *error_ptr) { 245 if (!m_read_thread.IsJoinable()) 246 return true; 247 248 Status error = m_read_thread.Join(nullptr); 249 return error.Success(); 250 } 251 252 size_t Communication::GetCachedBytes(void *dst, size_t dst_len) { 253 std::lock_guard<std::recursive_mutex> guard(m_bytes_mutex); 254 if (!m_bytes.empty()) { 255 // If DST is nullptr and we have a thread, then return the number of bytes 256 // that are available so the caller can call again 257 if (dst == nullptr) 258 return m_bytes.size(); 259 260 const size_t len = std::min<size_t>(dst_len, m_bytes.size()); 261 262 ::memcpy(dst, m_bytes.c_str(), len); 263 m_bytes.erase(m_bytes.begin(), m_bytes.begin() + len); 264 265 return len; 266 } 267 return 0; 268 } 269 270 void Communication::AppendBytesToCache(const uint8_t *bytes, size_t len, 271 bool broadcast, 272 ConnectionStatus status) { 273 LLDB_LOG(lldb_private::GetLogIfAllCategoriesSet(LIBLLDB_LOG_COMMUNICATION), 274 "{0} Communication::AppendBytesToCache (src = {1}, src_len = {2}, " 275 "broadcast = {3})", 276 this, bytes, (uint64_t)len, broadcast); 277 if ((bytes == nullptr || len == 0) && 278 (status != lldb::eConnectionStatusEndOfFile)) 279 return; 280 if (m_callback) { 281 // If the user registered a callback, then call it and do not broadcast 282 m_callback(m_callback_baton, bytes, len); 283 } else if (bytes != nullptr && len > 0) { 284 std::lock_guard<std::recursive_mutex> guard(m_bytes_mutex); 285 m_bytes.append((const char *)bytes, len); 286 if (broadcast) 287 BroadcastEventIfUnique(eBroadcastBitReadThreadGotBytes); 288 } 289 } 290 291 size_t Communication::ReadFromConnection(void *dst, size_t dst_len, 292 const Timeout<std::micro> &timeout, 293 ConnectionStatus &status, 294 Status *error_ptr) { 295 lldb::ConnectionSP connection_sp(m_connection_sp); 296 if (connection_sp) 297 return connection_sp->Read(dst, dst_len, timeout, status, error_ptr); 298 299 if (error_ptr) 300 error_ptr->SetErrorString("Invalid connection."); 301 status = eConnectionStatusNoConnection; 302 return 0; 303 } 304 305 bool Communication::ReadThreadIsRunning() { return m_read_thread_enabled; } 306 307 lldb::thread_result_t Communication::ReadThread(lldb::thread_arg_t p) { 308 Communication *comm = (Communication *)p; 309 310 Log *log(lldb_private::GetLogIfAllCategoriesSet(LIBLLDB_LOG_COMMUNICATION)); 311 312 LLDB_LOGF(log, "%p Communication::ReadThread () thread starting...", p); 313 314 uint8_t buf[1024]; 315 316 Status error; 317 ConnectionStatus status = eConnectionStatusSuccess; 318 bool done = false; 319 bool disconnect = false; 320 while (!done && comm->m_read_thread_enabled) { 321 size_t bytes_read = comm->ReadFromConnection( 322 buf, sizeof(buf), std::chrono::seconds(5), status, &error); 323 if (bytes_read > 0 || status == eConnectionStatusEndOfFile) 324 comm->AppendBytesToCache(buf, bytes_read, true, status); 325 326 switch (status) { 327 case eConnectionStatusSuccess: 328 break; 329 330 case eConnectionStatusEndOfFile: 331 done = true; 332 disconnect = comm->GetCloseOnEOF(); 333 break; 334 case eConnectionStatusError: // Check GetError() for details 335 if (error.GetType() == eErrorTypePOSIX && error.GetError() == EIO) { 336 // EIO on a pipe is usually caused by remote shutdown 337 disconnect = comm->GetCloseOnEOF(); 338 done = true; 339 } 340 if (error.Fail()) 341 LLDB_LOG(log, "error: {0}, status = {1}", error, 342 Communication::ConnectionStatusAsString(status)); 343 break; 344 case eConnectionStatusInterrupted: // Synchronization signal from 345 // SynchronizeWithReadThread() 346 // The connection returns eConnectionStatusInterrupted only when there is 347 // no input pending to be read, so we can signal that. 348 comm->BroadcastEvent(eBroadcastBitNoMorePendingInput); 349 break; 350 case eConnectionStatusNoConnection: // No connection 351 case eConnectionStatusLostConnection: // Lost connection while connected to 352 // a valid connection 353 done = true; 354 LLVM_FALLTHROUGH; 355 case eConnectionStatusTimedOut: // Request timed out 356 if (error.Fail()) 357 LLDB_LOG(log, "error: {0}, status = {1}", error, 358 Communication::ConnectionStatusAsString(status)); 359 break; 360 } 361 } 362 log = lldb_private::GetLogIfAllCategoriesSet(LIBLLDB_LOG_COMMUNICATION); 363 if (log) 364 LLDB_LOGF(log, "%p Communication::ReadThread () thread exiting...", p); 365 366 // Handle threads wishing to synchronize with us. 367 { 368 // Prevent new ones from showing up. 369 comm->m_read_thread_did_exit = true; 370 371 // Unblock any existing thread waiting for the synchronization signal. 372 comm->BroadcastEvent(eBroadcastBitNoMorePendingInput); 373 374 // Wait for the thread to finish... 375 std::lock_guard<std::mutex> guard(comm->m_synchronize_mutex); 376 // ... and disconnect. 377 if (disconnect) 378 comm->Disconnect(); 379 } 380 381 // Let clients know that this thread is exiting 382 comm->BroadcastEvent(eBroadcastBitReadThreadDidExit); 383 return {}; 384 } 385 386 void Communication::SetReadThreadBytesReceivedCallback( 387 ReadThreadBytesReceived callback, void *callback_baton) { 388 m_callback = callback; 389 m_callback_baton = callback_baton; 390 } 391 392 void Communication::SynchronizeWithReadThread() { 393 // Only one thread can do the synchronization dance at a time. 394 std::lock_guard<std::mutex> guard(m_synchronize_mutex); 395 396 // First start listening for the synchronization event. 397 ListenerSP listener_sp( 398 Listener::MakeListener("Communication::SyncronizeWithReadThread")); 399 listener_sp->StartListeningForEvents(this, eBroadcastBitNoMorePendingInput); 400 401 // If the thread is not running, there is no point in synchronizing. 402 if (!m_read_thread_enabled || m_read_thread_did_exit) 403 return; 404 405 // Notify the read thread. 406 m_connection_sp->InterruptRead(); 407 408 // Wait for the synchronization event. 409 EventSP event_sp; 410 listener_sp->GetEvent(event_sp, llvm::None); 411 } 412 413 void Communication::SetConnection(std::unique_ptr<Connection> connection) { 414 Disconnect(nullptr); 415 StopReadThread(nullptr); 416 m_connection_sp = std::move(connection); 417 } 418 419 std::string 420 Communication::ConnectionStatusAsString(lldb::ConnectionStatus status) { 421 switch (status) { 422 case eConnectionStatusSuccess: 423 return "success"; 424 case eConnectionStatusError: 425 return "error"; 426 case eConnectionStatusTimedOut: 427 return "timed out"; 428 case eConnectionStatusNoConnection: 429 return "no connection"; 430 case eConnectionStatusLostConnection: 431 return "lost connection"; 432 case eConnectionStatusEndOfFile: 433 return "end of file"; 434 case eConnectionStatusInterrupted: 435 return "interrupted"; 436 } 437 438 return "@" + std::to_string(status); 439 } 440