1 files changed, 404 insertions, 0 deletions
diff --git a/contrib/llvm-project/lldb/source/Plugins/Process/gdb-remote/GDBRemoteClientBase.cpp b/contrib/llvm-project/lldb/source/Plugins/Process/gdb-remote/GDBRemoteClientBase.cpp
new file mode 100644
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--- /dev/null
+++ b/contrib/llvm-project/lldb/source/Plugins/Process/gdb-remote/GDBRemoteClientBase.cpp
@@ -0,0 +1,404 @@
+//===-- GDBRemoteClientBase.cpp -------------------------------------------===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+
+#include "GDBRemoteClientBase.h"
+
+#include "llvm/ADT/StringExtras.h"
+
+#include "lldb/Target/UnixSignals.h"
+#include "lldb/Utility/LLDBAssert.h"
+
+#include "ProcessGDBRemoteLog.h"
+
+using namespace lldb;
+using namespace lldb_private;
+using namespace lldb_private::process_gdb_remote;
+using namespace std::chrono;
+
+// When we've sent a continue packet and are waiting for the target to stop,
+// we wake up the wait with this interval to make sure the stub hasn't gone
+// away while we were waiting.
+static const seconds kWakeupInterval(5);
+
+/////////////////////////
+// GDBRemoteClientBase //
+/////////////////////////
+
+GDBRemoteClientBase::ContinueDelegate::~ContinueDelegate() = default;
+
+GDBRemoteClientBase::GDBRemoteClientBase(const char *comm_name)
+    : GDBRemoteCommunication(), Broadcaster(nullptr, comm_name),
+      m_async_count(0), m_is_running(false), m_should_stop(false) {}
+
+StateType GDBRemoteClientBase::SendContinuePacketAndWaitForResponse(
+    ContinueDelegate &delegate, const UnixSignals &signals,
+    llvm::StringRef payload, std::chrono::seconds interrupt_timeout,
+    StringExtractorGDBRemote &response) {
+  Log *log = GetLog(GDBRLog::Process);
+  response.Clear();
+
+  {
+    std::lock_guard<std::mutex> lock(m_mutex);
+    m_continue_packet = std::string(payload);
+    m_should_stop = false;
+  }
+  ContinueLock cont_lock(*this);
+  if (!cont_lock)
+    return eStateInvalid;
+  OnRunPacketSent(true);
+  // The main ReadPacket loop wakes up at computed_timeout intervals, just to 
+  // check that the connection hasn't dropped.  When we wake up we also check
+  // whether there is an interrupt request that has reached its endpoint.
+  // If we want a shorter interrupt timeout that kWakeupInterval, we need to 
+  // choose the shorter interval for the wake up as well.
+  std::chrono::seconds computed_timeout = std::min(interrupt_timeout, 
+                                                   kWakeupInterval);
+  for (;;) {
+    PacketResult read_result = ReadPacket(response, computed_timeout, false);
+    // Reset the computed_timeout to the default value in case we are going
+    // round again.
+    computed_timeout = std::min(interrupt_timeout, kWakeupInterval);
+    switch (read_result) {
+    case PacketResult::ErrorReplyTimeout: {
+      std::lock_guard<std::mutex> lock(m_mutex);
+      if (m_async_count == 0) {
+        continue;
+      }
+      auto cur_time = steady_clock::now();
+      if (cur_time >= m_interrupt_endpoint)
+        return eStateInvalid;
+      else {
+        // We woke up and found an interrupt is in flight, but we haven't
+        // exceeded the interrupt wait time.  So reset the wait time to the
+        // time left till the interrupt timeout.  But don't wait longer
+        // than our wakeup timeout.
+        auto new_wait = m_interrupt_endpoint - cur_time;
+        computed_timeout = std::min(kWakeupInterval,
+            std::chrono::duration_cast<std::chrono::seconds>(new_wait));
+        continue;
+      }
+      break;
+    }
+    case PacketResult::Success:
+      break;
+    default:
+      LLDB_LOGF(log, "GDBRemoteClientBase::%s () ReadPacket(...) => false",
+                __FUNCTION__);
+      return eStateInvalid;
+    }
+    if (response.Empty())
+      return eStateInvalid;
+
+    const char stop_type = response.GetChar();
+    LLDB_LOGF(log, "GDBRemoteClientBase::%s () got packet: %s", __FUNCTION__,
+              response.GetStringRef().data());
+
+    switch (stop_type) {
+    case 'W':
+    case 'X':
+      return eStateExited;
+    case 'E':
+      // ERROR
+      return eStateInvalid;
+    default:
+      LLDB_LOGF(log, "GDBRemoteClientBase::%s () unrecognized async packet",
+                __FUNCTION__);
+      return eStateInvalid;
+    case 'O': {
+      std::string inferior_stdout;
+      response.GetHexByteString(inferior_stdout);
+      delegate.HandleAsyncStdout(inferior_stdout);
+      break;
+    }
+    case 'A':
+      delegate.HandleAsyncMisc(
+          llvm::StringRef(response.GetStringRef()).substr(1));
+      break;
+    case 'J':
+      delegate.HandleAsyncStructuredDataPacket(response.GetStringRef());
+      break;
+    case 'T':
+    case 'S':
+      // Do this with the continue lock held.
+      const bool should_stop = ShouldStop(signals, response);
+      response.SetFilePos(0);
+
+      // The packet we should resume with. In the future we should check our
+      // thread list and "do the right thing" for new threads that show up
+      // while we stop and run async packets. Setting the packet to 'c' to
+      // continue all threads is the right thing to do 99.99% of the time
+      // because if a thread was single stepping, and we sent an interrupt, we
+      // will notice above that we didn't stop due to an interrupt but stopped
+      // due to stepping and we would _not_ continue. This packet may get
+      // modified by the async actions (e.g. to send a signal).
+      m_continue_packet = 'c';
+      cont_lock.unlock();
+
+      delegate.HandleStopReply();
+      if (should_stop)
+        return eStateStopped;
+
+      switch (cont_lock.lock()) {
+      case ContinueLock::LockResult::Success:
+        break;
+      case ContinueLock::LockResult::Failed:
+        return eStateInvalid;
+      case ContinueLock::LockResult::Cancelled:
+        return eStateStopped;
+      }
+      OnRunPacketSent(false);
+      break;
+    }
+  }
+}
+
+bool GDBRemoteClientBase::SendAsyncSignal(
+    int signo, std::chrono::seconds interrupt_timeout) {
+  Lock lock(*this, interrupt_timeout);
+  if (!lock || !lock.DidInterrupt())
+    return false;
+
+  m_continue_packet = 'C';
+  m_continue_packet += llvm::hexdigit((signo / 16) % 16);
+  m_continue_packet += llvm::hexdigit(signo % 16);
+  return true;
+}
+
+bool GDBRemoteClientBase::Interrupt(std::chrono::seconds interrupt_timeout) {
+  Lock lock(*this, interrupt_timeout);
+  if (!lock.DidInterrupt())
+    return false;
+  m_should_stop = true;
+  return true;
+}
+
+GDBRemoteCommunication::PacketResult
+GDBRemoteClientBase::SendPacketAndWaitForResponse(
+    llvm::StringRef payload, StringExtractorGDBRemote &response,
+    std::chrono::seconds interrupt_timeout) {
+  Lock lock(*this, interrupt_timeout);
+  if (!lock) {
+    if (Log *log = GetLog(GDBRLog::Process))
+      LLDB_LOGF(log,
+                "GDBRemoteClientBase::%s failed to get mutex, not sending "
+                "packet '%.*s'",
+                __FUNCTION__, int(payload.size()), payload.data());
+    return PacketResult::ErrorSendFailed;
+  }
+
+  return SendPacketAndWaitForResponseNoLock(payload, response);
+}
+
+GDBRemoteCommunication::PacketResult
+GDBRemoteClientBase::ReadPacketWithOutputSupport(
+    StringExtractorGDBRemote &response, Timeout<std::micro> timeout,
+    bool sync_on_timeout,
+    llvm::function_ref<void(llvm::StringRef)> output_callback) {
+  auto result = ReadPacket(response, timeout, sync_on_timeout);
+  while (result == PacketResult::Success && response.IsNormalResponse() &&
+         response.PeekChar() == 'O') {
+    response.GetChar();
+    std::string output;
+    if (response.GetHexByteString(output))
+      output_callback(output);
+    result = ReadPacket(response, timeout, sync_on_timeout);
+  }
+  return result;
+}
+
+GDBRemoteCommunication::PacketResult
+GDBRemoteClientBase::SendPacketAndReceiveResponseWithOutputSupport(
+    llvm::StringRef payload, StringExtractorGDBRemote &response,
+    std::chrono::seconds interrupt_timeout,
+    llvm::function_ref<void(llvm::StringRef)> output_callback) {
+  Lock lock(*this, interrupt_timeout);
+  if (!lock) {
+    if (Log *log = GetLog(GDBRLog::Process))
+      LLDB_LOGF(log,
+                "GDBRemoteClientBase::%s failed to get mutex, not sending "
+                "packet '%.*s'",
+                __FUNCTION__, int(payload.size()), payload.data());
+    return PacketResult::ErrorSendFailed;
+  }
+
+  PacketResult packet_result = SendPacketNoLock(payload);
+  if (packet_result != PacketResult::Success)
+    return packet_result;
+
+  return ReadPacketWithOutputSupport(response, GetPacketTimeout(), true,
+                                     output_callback);
+}
+
+GDBRemoteCommunication::PacketResult
+GDBRemoteClientBase::SendPacketAndWaitForResponseNoLock(
+    llvm::StringRef payload, StringExtractorGDBRemote &response) {
+  PacketResult packet_result = SendPacketNoLock(payload);
+  if (packet_result != PacketResult::Success)
+    return packet_result;
+
+  const size_t max_response_retries = 3;
+  for (size_t i = 0; i < max_response_retries; ++i) {
+    packet_result = ReadPacket(response, GetPacketTimeout(), true);
+    // Make sure we received a response
+    if (packet_result != PacketResult::Success)
+      return packet_result;
+    // Make sure our response is valid for the payload that was sent
+    if (response.ValidateResponse())
+      return packet_result;
+    // Response says it wasn't valid
+    Log *log = GetLog(GDBRLog::Packets);
+    LLDB_LOGF(
+        log,
+        "error: packet with payload \"%.*s\" got invalid response \"%s\": %s",
+        int(payload.size()), payload.data(), response.GetStringRef().data(),
+        (i == (max_response_retries - 1))
+            ? "using invalid response and giving up"
+            : "ignoring response and waiting for another");
+  }
+  return packet_result;
+}
+
+bool GDBRemoteClientBase::ShouldStop(const UnixSignals &signals,
+                                     StringExtractorGDBRemote &response) {
+  std::lock_guard<std::mutex> lock(m_mutex);
+
+  if (m_async_count == 0)
+    return true; // We were not interrupted. The process stopped on its own.
+
+  // Older debugserver stubs (before April 2016) can return two stop-reply
+  // packets in response to a ^C packet. Additionally, all debugservers still
+  // return two stop replies if the inferior stops due to some other reason
+  // before the remote stub manages to interrupt it. We need to wait for this
+  // additional packet to make sure the packet sequence does not get skewed.
+  StringExtractorGDBRemote extra_stop_reply_packet;
+  ReadPacket(extra_stop_reply_packet, milliseconds(100), false);
+
+  // Interrupting is typically done using SIGSTOP or SIGINT, so if the process
+  // stops with some other signal, we definitely want to stop.
+  const uint8_t signo = response.GetHexU8(UINT8_MAX);
+  if (signo != signals.GetSignalNumberFromName("SIGSTOP") &&
+      signo != signals.GetSignalNumberFromName("SIGINT"))
+    return true;
+
+  // We probably only stopped to perform some async processing, so continue
+  // after that is done.
+  // TODO: This is not 100% correct, as the process may have been stopped with
+  // SIGINT or SIGSTOP that was not caused by us (e.g. raise(SIGINT)). This will
+  // normally cause a stop, but if it's done concurrently with a async
+  // interrupt, that stop will get eaten (llvm.org/pr20231).
+  return false;
+}
+
+void GDBRemoteClientBase::OnRunPacketSent(bool first) {
+  if (first)
+    BroadcastEvent(eBroadcastBitRunPacketSent, nullptr);
+}
+
+///////////////////////////////////////
+// GDBRemoteClientBase::ContinueLock //
+///////////////////////////////////////
+
+GDBRemoteClientBase::ContinueLock::ContinueLock(GDBRemoteClientBase &comm)
+    : m_comm(comm), m_acquired(false) {
+  lock();
+}
+
+GDBRemoteClientBase::ContinueLock::~ContinueLock() {
+  if (m_acquired)
+    unlock();
+}
+
+void GDBRemoteClientBase::ContinueLock::unlock() {
+  lldbassert(m_acquired);
+  {
+    std::unique_lock<std::mutex> lock(m_comm.m_mutex);
+    m_comm.m_is_running = false;
+  }
+  m_comm.m_cv.notify_all();
+  m_acquired = false;
+}
+
+GDBRemoteClientBase::ContinueLock::LockResult
+GDBRemoteClientBase::ContinueLock::lock() {
+  Log *log = GetLog(GDBRLog::Process);
+  LLDB_LOGF(log, "GDBRemoteClientBase::ContinueLock::%s() resuming with %s",
+            __FUNCTION__, m_comm.m_continue_packet.c_str());
+
+  lldbassert(!m_acquired);
+  std::unique_lock<std::mutex> lock(m_comm.m_mutex);
+  m_comm.m_cv.wait(lock, [this] { return m_comm.m_async_count == 0; });
+  if (m_comm.m_should_stop) {
+    m_comm.m_should_stop = false;
+    LLDB_LOGF(log, "GDBRemoteClientBase::ContinueLock::%s() cancelled",
+              __FUNCTION__);
+    return LockResult::Cancelled;
+  }
+  if (m_comm.SendPacketNoLock(m_comm.m_continue_packet) !=
+      PacketResult::Success)
+    return LockResult::Failed;
+
+  lldbassert(!m_comm.m_is_running);
+  m_comm.m_is_running = true;
+  m_acquired = true;
+  return LockResult::Success;
+}
+
+///////////////////////////////
+// GDBRemoteClientBase::Lock //
+///////////////////////////////
+
+GDBRemoteClientBase::Lock::Lock(GDBRemoteClientBase &comm,
+                                std::chrono::seconds interrupt_timeout)
+    : m_async_lock(comm.m_async_mutex, std::defer_lock), m_comm(comm),
+      m_interrupt_timeout(interrupt_timeout), m_acquired(false),
+      m_did_interrupt(false) {
+  SyncWithContinueThread();
+  if (m_acquired)
+    m_async_lock.lock();
+}
+
+void GDBRemoteClientBase::Lock::SyncWithContinueThread() {
+  Log *log = GetLog(GDBRLog::Process|GDBRLog::Packets);
+  std::unique_lock<std::mutex> lock(m_comm.m_mutex);
+  if (m_comm.m_is_running && m_interrupt_timeout == std::chrono::seconds(0))
+    return; // We were asked to avoid interrupting the sender. Lock is not
+            // acquired.
+
+  ++m_comm.m_async_count;
+  if (m_comm.m_is_running) {
+    if (m_comm.m_async_count == 1) {
+      // The sender has sent the continue packet and we are the first async
+      // packet. Let's interrupt it.
+      const char ctrl_c = '\x03';
+      ConnectionStatus status = eConnectionStatusSuccess;
+      size_t bytes_written = m_comm.Write(&ctrl_c, 1, status, nullptr);
+      if (bytes_written == 0) {
+        --m_comm.m_async_count;
+        LLDB_LOGF(log, "GDBRemoteClientBase::Lock::Lock failed to send "
+                       "interrupt packet");
+        return;
+      }
+      m_comm.m_interrupt_endpoint = steady_clock::now() + m_interrupt_timeout;
+      if (log)
+        log->PutCString("GDBRemoteClientBase::Lock::Lock sent packet: \\x03");
+    }
+    m_comm.m_cv.wait(lock, [this] { return !m_comm.m_is_running; });
+    m_did_interrupt = true;
+  }
+  m_acquired = true;
+}
+
+GDBRemoteClientBase::Lock::~Lock() {
+  if (!m_acquired)
+    return;
+  {
+    std::unique_lock<std::mutex> lock(m_comm.m_mutex);
+    --m_comm.m_async_count;
+  }
+  m_comm.m_cv.notify_one();
+}