[Lldb-commits] [lldb] [lldb] Updated lldb-server to spawn the child process and share socket on Windows (PR #101283)

Dmitry Vasilyev via lldb-commits lldb-commits at lists.llvm.org
Tue Jul 30 21:12:55 PDT 2024


https://github.com/slydiman created https://github.com/llvm/llvm-project/pull/101283

`lldb-server --server` works on Windows now w/o multithreading. The rest functionality remains unchanged.

Added also PipeWindows::WriteWithTimeout(), fixed PipeWindows::ReadWithTimeout() and missing initialization of  m_read_overlapped.hEvent in the constructor PipeWindows(lldb::pipe_t read, lldb::pipe_t write).

Fixes #90923, fixes #56346.

This is the part 1 of the replacement of #100670.

In the part 2 I plan to switch `lldb-server gdbserver` to use `--fd` and listen a common gdb port for all gdbserver connections. Then we can remove gdb port mapping to fix #97537.

>From 28ee2d294000852cc8b0a40db55b0619e9d257c9 Mon Sep 17 00:00:00 2001
From: Dmitry Vasilyev <dvassiliev at accesssoftek.com>
Date: Wed, 31 Jul 2024 05:41:21 +0400
Subject: [PATCH] [lldb] Updated lldb-server to spawn the child process and
 share socket on Windows

`lldb-server --server` works on Windows now w/o multithreading. The rest functionality remains unchanged.

Added also PipeWindows::WriteWithTimeout(), fixed PipeWindows::ReadWithTimeout() and missing initialization of  m_read_overlapped.hEvent in the constructor PipeWindows(lldb::pipe_t read, lldb::pipe_t write).

Fixes #90923, fixes #56346.

This is the part 1 of the replacement of #100670.

In the part 2 I plan to switch `lldb-server gdbserver` to use --fd and listen a common gdb port for all gdbserver connections. Then we can remove gdb port mapping to fix #97537.
---
 lldb/include/lldb/Host/windows/PipeWindows.h  |   3 +
 lldb/source/Host/windows/PipeWindows.cpp      | 128 ++++---
 .../GDBRemoteCommunicationServerPlatform.cpp  |  34 ++
 .../GDBRemoteCommunicationServerPlatform.h    |   2 +-
 .../tools/lldb-server/LLDBServerUtilities.cpp |   2 +
 lldb/tools/lldb-server/lldb-platform.cpp      | 316 +++++++++++++++---
 6 files changed, 404 insertions(+), 81 deletions(-)

diff --git a/lldb/include/lldb/Host/windows/PipeWindows.h b/lldb/include/lldb/Host/windows/PipeWindows.h
index 4b5be28d7ae6c..c99cf52be46c1 100644
--- a/lldb/include/lldb/Host/windows/PipeWindows.h
+++ b/lldb/include/lldb/Host/windows/PipeWindows.h
@@ -61,6 +61,9 @@ class PipeWindows : public PipeBase {
   Status Delete(llvm::StringRef name) override;
 
   Status Write(const void *buf, size_t size, size_t &bytes_written) override;
+  Status WriteWithTimeout(const void *buf, size_t size,
+                          const std::chrono::microseconds &timeout,
+                          size_t &bytes_written);
   Status ReadWithTimeout(void *buf, size_t size,
                          const std::chrono::microseconds &timeout,
                          size_t &bytes_read) override;
diff --git a/lldb/source/Host/windows/PipeWindows.cpp b/lldb/source/Host/windows/PipeWindows.cpp
index c82c919607b5b..318d5abbed74d 100644
--- a/lldb/source/Host/windows/PipeWindows.cpp
+++ b/lldb/source/Host/windows/PipeWindows.cpp
@@ -58,7 +58,10 @@ PipeWindows::PipeWindows(pipe_t read, pipe_t write)
   }
 
   ZeroMemory(&m_read_overlapped, sizeof(m_read_overlapped));
+  m_read_overlapped.hEvent = ::CreateEventA(nullptr, TRUE, FALSE, nullptr);
+
   ZeroMemory(&m_write_overlapped, sizeof(m_write_overlapped));
+  m_write_overlapped.hEvent = ::CreateEventA(nullptr, TRUE, FALSE, nullptr);
 }
 
 PipeWindows::~PipeWindows() { Close(); }
@@ -77,6 +80,7 @@ Status PipeWindows::CreateNew(bool child_process_inherit) {
 
   m_write_fd = _open_osfhandle((intptr_t)m_write, _O_WRONLY);
   ZeroMemory(&m_write_overlapped, sizeof(m_write_overlapped));
+  m_write_overlapped.hEvent = ::CreateEventA(nullptr, TRUE, FALSE, nullptr);
 
   return Status();
 }
@@ -202,6 +206,7 @@ Status PipeWindows::OpenNamedPipe(llvm::StringRef name,
     m_write_fd = _open_osfhandle((intptr_t)m_write, _O_WRONLY);
 
     ZeroMemory(&m_write_overlapped, sizeof(m_write_overlapped));
+    m_write_overlapped.hEvent = ::CreateEventA(nullptr, TRUE, FALSE, nullptr);
   }
 
   return Status();
@@ -228,6 +233,8 @@ int PipeWindows::ReleaseWriteFileDescriptor() {
     return PipeWindows::kInvalidDescriptor;
   int result = m_write_fd;
   m_write_fd = PipeWindows::kInvalidDescriptor;
+  if (m_write_overlapped.hEvent)
+    ::CloseHandle(m_write_overlapped.hEvent);
   m_write = INVALID_HANDLE_VALUE;
   ZeroMemory(&m_write_overlapped, sizeof(m_write_overlapped));
   return result;
@@ -250,6 +257,9 @@ void PipeWindows::CloseWriteFileDescriptor() {
   if (!CanWrite())
     return;
 
+  if (m_write_overlapped.hEvent)
+    ::CloseHandle(m_write_overlapped.hEvent);
+
   _close(m_write_fd);
   m_write = INVALID_HANDLE_VALUE;
   m_write_fd = PipeWindows::kInvalidDescriptor;
@@ -283,54 +293,94 @@ Status PipeWindows::ReadWithTimeout(void *buf, size_t size,
   DWORD sys_bytes_read = size;
   BOOL result = ::ReadFile(m_read, buf, sys_bytes_read, &sys_bytes_read,
                            &m_read_overlapped);
-  if (!result && GetLastError() != ERROR_IO_PENDING)
-    return Status(::GetLastError(), eErrorTypeWin32);
-
-  DWORD timeout = (duration == std::chrono::microseconds::zero())
-                      ? INFINITE
-                      : duration.count() * 1000;
-  DWORD wait_result = ::WaitForSingleObject(m_read_overlapped.hEvent, timeout);
-  if (wait_result != WAIT_OBJECT_0) {
-    // The operation probably failed.  However, if it timed out, we need to
-    // cancel the I/O. Between the time we returned from WaitForSingleObject
-    // and the time we call CancelIoEx, the operation may complete.  If that
-    // hapens, CancelIoEx will fail and return ERROR_NOT_FOUND. If that
-    // happens, the original operation should be considered to have been
-    // successful.
-    bool failed = true;
-    DWORD failure_error = ::GetLastError();
-    if (wait_result == WAIT_TIMEOUT) {
-      BOOL cancel_result = CancelIoEx(m_read, &m_read_overlapped);
-      if (!cancel_result && GetLastError() == ERROR_NOT_FOUND)
-        failed = false;
+  if (!result) {
+    if (GetLastError() != ERROR_IO_PENDING)
+      return Status(::GetLastError(), eErrorTypeWin32);
+    else {
+      DWORD timeout = (duration == std::chrono::microseconds::zero())
+                          ? INFINITE
+                          : duration.count() * 1000;
+      DWORD wait_result =
+          ::WaitForSingleObject(m_read_overlapped.hEvent, timeout);
+      if (wait_result != WAIT_OBJECT_0) {
+        // The operation probably failed.  However, if it timed out, we need to
+        // cancel the I/O. Between the time we returned from WaitForSingleObject
+        // and the time we call CancelIoEx, the operation may complete.  If that
+        // hapens, CancelIoEx will fail and return ERROR_NOT_FOUND. If that
+        // happens, the original operation should be considered to have been
+        // successful.
+        bool failed = true;
+        DWORD failure_error = ::GetLastError();
+        if (wait_result == WAIT_TIMEOUT) {
+          BOOL cancel_result = CancelIoEx(m_read, &m_read_overlapped);
+          if (!cancel_result && GetLastError() == ERROR_NOT_FOUND)
+            failed = false;
+        }
+        if (failed)
+          return Status(failure_error, eErrorTypeWin32);
+      }
+
+      // Now we call GetOverlappedResult setting bWait to false, since we've
+      // already waited as long as we're willing to.
+      if (!GetOverlappedResult(m_read, &m_read_overlapped, &sys_bytes_read,
+                               FALSE))
+        return Status(::GetLastError(), eErrorTypeWin32);
     }
-    if (failed)
-      return Status(failure_error, eErrorTypeWin32);
   }
-
-  // Now we call GetOverlappedResult setting bWait to false, since we've
-  // already waited as long as we're willing to.
-  if (!GetOverlappedResult(m_read, &m_read_overlapped, &sys_bytes_read, FALSE))
-    return Status(::GetLastError(), eErrorTypeWin32);
-
   bytes_read = sys_bytes_read;
   return Status();
 }
 
-Status PipeWindows::Write(const void *buf, size_t num_bytes,
-                          size_t &bytes_written) {
+Status PipeWindows::WriteWithTimeout(const void *buf, size_t size,
+                                     const std::chrono::microseconds &duration,
+                                     size_t &bytes_written) {
   if (!CanWrite())
     return Status(ERROR_INVALID_HANDLE, eErrorTypeWin32);
 
-  DWORD sys_bytes_written = 0;
-  BOOL write_result = ::WriteFile(m_write, buf, num_bytes, &sys_bytes_written,
-                                  &m_write_overlapped);
-  if (!write_result && GetLastError() != ERROR_IO_PENDING)
-    return Status(::GetLastError(), eErrorTypeWin32);
+  bytes_written = 0;
+  DWORD sys_bytes_write = size;
+  BOOL result = ::WriteFile(m_write, buf, sys_bytes_write, &sys_bytes_write,
+                            &m_write_overlapped);
+  if (!result) {
+    if (GetLastError() != ERROR_IO_PENDING)
+      return Status(::GetLastError(), eErrorTypeWin32);
+    else {
+      DWORD timeout = (duration == std::chrono::microseconds::zero())
+                          ? INFINITE
+                          : duration.count() * 1000;
+      DWORD wait_result =
+          ::WaitForSingleObject(m_write_overlapped.hEvent, timeout);
+      if (wait_result != WAIT_OBJECT_0) {
+        // The operation probably failed.  However, if it timed out, we need to
+        // cancel the I/O. Between the time we returned from WaitForSingleObject
+        // and the time we call CancelIoEx, the operation may complete.  If that
+        // hapens, CancelIoEx will fail and return ERROR_NOT_FOUND. If that
+        // happens, the original operation should be considered to have been
+        // successful.
+        bool failed = true;
+        DWORD failure_error = ::GetLastError();
+        if (wait_result == WAIT_TIMEOUT) {
+          BOOL cancel_result = CancelIoEx(m_write, &m_write_overlapped);
+          if (!cancel_result && GetLastError() == ERROR_NOT_FOUND)
+            failed = false;
+        }
+        if (failed)
+          return Status(failure_error, eErrorTypeWin32);
+      }
+
+      // Now we call GetOverlappedResult setting bWait to false, since we've
+      // already waited as long as we're willing to.
+      if (!GetOverlappedResult(m_write, &m_write_overlapped, &sys_bytes_write,
+                               FALSE))
+        return Status(::GetLastError(), eErrorTypeWin32);
+    }
+  }
 
-  BOOL result = GetOverlappedResult(m_write, &m_write_overlapped,
-                                    &sys_bytes_written, TRUE);
-  if (!result)
-    return Status(::GetLastError(), eErrorTypeWin32);
+  bytes_written = sys_bytes_write;
   return Status();
 }
+
+Status PipeWindows::Write(const void *buf, size_t size, size_t &bytes_written) {
+  return WriteWithTimeout(buf, size, std::chrono::microseconds::zero(),
+                          bytes_written);
+}
diff --git a/lldb/source/Plugins/Process/gdb-remote/GDBRemoteCommunicationServerPlatform.cpp b/lldb/source/Plugins/Process/gdb-remote/GDBRemoteCommunicationServerPlatform.cpp
index 65f1cc12ba307..18824a6cb08ca 100644
--- a/lldb/source/Plugins/Process/gdb-remote/GDBRemoteCommunicationServerPlatform.cpp
+++ b/lldb/source/Plugins/Process/gdb-remote/GDBRemoteCommunicationServerPlatform.cpp
@@ -159,6 +159,40 @@ GDBRemoteCommunicationServerPlatform::GDBRemoteCommunicationServerPlatform(
 GDBRemoteCommunicationServerPlatform::~GDBRemoteCommunicationServerPlatform() =
     default;
 
+void GDBRemoteCommunicationServerPlatform::Proc(
+    const lldb_private::Args &args) {
+  if (!IsConnected())
+    return;
+
+  if (args.GetArgumentCount() > 0) {
+    lldb::pid_t pid = LLDB_INVALID_PROCESS_ID;
+    std::optional<uint16_t> port;
+    std::string socket_name;
+    Status error = LaunchGDBServer(args,
+                                   "", // hostname
+                                   pid, port, socket_name);
+    if (error.Success())
+      SetPendingGdbServer(pid, *port, socket_name);
+  }
+
+  bool interrupt = false;
+  bool done = false;
+  Status error;
+  while (!interrupt && !done) {
+    if (GetPacketAndSendResponse(std::nullopt, error, interrupt, done) !=
+        GDBRemoteCommunication::PacketResult::Success)
+      break;
+  }
+
+  if (error.Fail()) {
+    Log *log = GetLog(LLDBLog::Platform);
+    LLDB_LOGF(log,
+              "GDBRemoteCommunicationServerPlatform::%s() "
+              "GetPacketAndSendResponse: %s",
+              __FUNCTION__, error.AsCString());
+  }
+}
+
 Status GDBRemoteCommunicationServerPlatform::LaunchGDBServer(
     const lldb_private::Args &args, std::string hostname, lldb::pid_t &pid,
     std::optional<uint16_t> &port, std::string &socket_name) {
diff --git a/lldb/source/Plugins/Process/gdb-remote/GDBRemoteCommunicationServerPlatform.h b/lldb/source/Plugins/Process/gdb-remote/GDBRemoteCommunicationServerPlatform.h
index 1853025466cf0..2f3f313c917c4 100644
--- a/lldb/source/Plugins/Process/gdb-remote/GDBRemoteCommunicationServerPlatform.h
+++ b/lldb/source/Plugins/Process/gdb-remote/GDBRemoteCommunicationServerPlatform.h
@@ -85,7 +85,7 @@ class GDBRemoteCommunicationServerPlatform
 
   void SetPortOffset(uint16_t port_offset);
 
-  void SetInferiorArguments(const lldb_private::Args &args);
+  void Proc(const lldb_private::Args &args);
 
   // Set port if you want to use a specific port number.
   // Otherwise port will be set to the port that was chosen for you.
diff --git a/lldb/tools/lldb-server/LLDBServerUtilities.cpp b/lldb/tools/lldb-server/LLDBServerUtilities.cpp
index c3a8df19e969e..5facfbf3105e9 100644
--- a/lldb/tools/lldb-server/LLDBServerUtilities.cpp
+++ b/lldb/tools/lldb-server/LLDBServerUtilities.cpp
@@ -27,11 +27,13 @@ class TestLogHandler : public LogHandler {
       : m_stream_sp(stream_sp) {}
 
   void Emit(llvm::StringRef message) override {
+    std::lock_guard<std::mutex> guard(m_mutex);
     (*m_stream_sp) << message;
     m_stream_sp->flush();
   }
 
 private:
+  std::mutex m_mutex;
   std::shared_ptr<raw_ostream> m_stream_sp;
 };
 
diff --git a/lldb/tools/lldb-server/lldb-platform.cpp b/lldb/tools/lldb-server/lldb-platform.cpp
index 7148a1d2a3094..f14b90b1c28fc 100644
--- a/lldb/tools/lldb-server/lldb-platform.cpp
+++ b/lldb/tools/lldb-server/lldb-platform.cpp
@@ -22,6 +22,7 @@
 #include <optional>
 
 #include "llvm/Support/FileSystem.h"
+#include "llvm/Support/ScopedPrinter.h"
 #include "llvm/Support/WithColor.h"
 #include "llvm/Support/raw_ostream.h"
 
@@ -32,8 +33,10 @@
 #include "lldb/Host/ConnectionFileDescriptor.h"
 #include "lldb/Host/HostGetOpt.h"
 #include "lldb/Host/OptionParser.h"
+#include "lldb/Host/Socket.h"
 #include "lldb/Host/common/TCPSocket.h"
 #include "lldb/Utility/FileSpec.h"
+#include "lldb/Utility/LLDBLog.h"
 #include "lldb/Utility/Status.h"
 
 using namespace lldb;
@@ -60,6 +63,9 @@ static struct option g_long_options[] = {
     {"max-gdbserver-port", required_argument, nullptr, 'M'},
     {"socket-file", required_argument, nullptr, 'f'},
     {"server", no_argument, &g_server, 1},
+#if defined(_WIN32)
+    {"accept", required_argument, nullptr, 'a'},
+#endif
     {nullptr, 0, nullptr, 0}};
 
 #if defined(__APPLE__)
@@ -114,6 +120,218 @@ static Status save_socket_id_to_file(const std::string &socket_id,
   return status;
 }
 
+static GDBRemoteCommunicationServerPlatform::PortMap gdbserver_portmap;
+static std::mutex gdbserver_portmap_mutex;
+
+#if defined(_WIN32)
+static void SpawnProcessReaped(lldb::pid_t pid, int signal, int status) {
+  std::lock_guard<std::mutex> guard(gdbserver_portmap_mutex);
+  gdbserver_portmap.FreePortForProcess(pid);
+}
+
+static bool SpawnProcessParent(const char *progname, Connection *conn,
+                               uint16_t gdb_port, uint16_t port_offset,
+                               const lldb_private::Args &args,
+                               const std::string &log_file,
+                               const StringRef log_channels) {
+  Log *log = GetLog(LLDBLog::Platform);
+  Pipe socket_pipe;
+  Status error = socket_pipe.CreateNew(true);
+  if (error.Fail()) {
+    LLDB_LOGF(log,
+              "lldb-platform parent: "
+              "cannot create pipe: %s",
+              error.AsCString());
+    return false;
+  }
+
+  ProcessLaunchInfo launch_info;
+  FileSpec self_spec(progname, FileSpec::Style::native);
+  launch_info.SetExecutableFile(self_spec, true);
+  Args &self_args = launch_info.GetArguments();
+  self_args.AppendArgument(llvm::StringRef("platform"));
+  self_args.AppendArgument(llvm::StringRef("--accept"));
+  self_args.AppendArgument(llvm::to_string(socket_pipe.GetReadPipe()));
+  if (gdb_port) {
+    self_args.AppendArgument(llvm::StringRef("--gdbserver-port"));
+    self_args.AppendArgument(llvm::to_string(gdb_port));
+  }
+  if (port_offset > 0) {
+    self_args.AppendArgument(llvm::StringRef("--port-offset"));
+    self_args.AppendArgument(llvm::to_string(port_offset));
+  }
+  if (!log_file.empty()) {
+    self_args.AppendArgument(llvm::StringRef("--log-file"));
+    self_args.AppendArgument(log_file);
+  }
+  if (!log_channels.empty()) {
+    self_args.AppendArgument(llvm::StringRef("--log-channels"));
+    self_args.AppendArgument(log_channels);
+  }
+  if (args.GetArgumentCount() > 0) {
+    self_args.AppendArgument("--");
+    self_args.AppendArguments(args);
+  }
+
+  launch_info.SetLaunchInSeparateProcessGroup(false);
+  launch_info.SetMonitorProcessCallback(&SpawnProcessReaped);
+
+  // Copy the current environment.
+  // WSASocket(FROM_PROTOCOL_INFO) will fail in the child process
+  // with the error WSAEPROVIDERFAILEDINIT if the SystemRoot is missing
+  // in the environment.
+  launch_info.GetEnvironment() = Host::GetEnvironment();
+
+  launch_info.GetFlags().Set(eLaunchFlagDisableSTDIO);
+
+  launch_info.AppendCloseFileAction(socket_pipe.GetWriteFileDescriptor());
+
+  // Close STDIN, STDOUT and STDERR.
+  launch_info.AppendCloseFileAction(STDIN_FILENO);
+  launch_info.AppendCloseFileAction(STDOUT_FILENO);
+  launch_info.AppendCloseFileAction(STDERR_FILENO);
+
+  // Redirect STDIN, STDOUT and STDERR to "/dev/null".
+  launch_info.AppendSuppressFileAction(STDIN_FILENO, true, false);
+  launch_info.AppendSuppressFileAction(STDOUT_FILENO, false, true);
+  launch_info.AppendSuppressFileAction(STDERR_FILENO, false, true);
+
+  std::string cmd;
+  self_args.GetCommandString(cmd);
+
+  error = Host::LaunchProcess(launch_info);
+  if (error.Fail()) {
+    LLDB_LOGF(log,
+              "lldb-platform parent: "
+              "cannot launch child process for connection: %s",
+              error.AsCString());
+    return false;
+  }
+
+  lldb::pid_t childPid = launch_info.GetProcessID();
+  if (childPid == LLDB_INVALID_PROCESS_ID) {
+    LLDB_LOGF(log, "lldb-platform parent: "
+                   "cannot launch child process for connection: invalid pid");
+    return false;
+  }
+  LLDB_LOGF(log,
+            "lldb-platform parent: "
+            "launched '%s', pid=0x%x",
+            cmd.c_str(), childPid);
+
+  {
+    std::lock_guard<std::mutex> guard(gdbserver_portmap_mutex);
+    gdbserver_portmap.AssociatePortWithProcess(gdb_port, childPid);
+  }
+
+  if (socket_pipe.CanRead())
+    socket_pipe.CloseReadFileDescriptor();
+  if (!socket_pipe.CanWrite()) {
+    LLDB_LOGF(log, "lldb-platform parent: "
+                   "cannot write to socket_pipe");
+    Host::Kill(childPid, SIGTERM);
+    return false;
+  }
+
+  const TCPSocket &socket =
+      static_cast<const TCPSocket &>(*conn->GetReadObject());
+  NativeSocket nativeSocket = socket.GetNativeSocket();
+
+  WSAPROTOCOL_INFO protocol_info;
+  if (::WSADuplicateSocket(nativeSocket, childPid, &protocol_info) ==
+      SOCKET_ERROR) {
+    LLDB_LOGF(log,
+              "lldb-platform parent: "
+              "WSADuplicateSocket() failed, error: %d",
+              ::WSAGetLastError());
+    Host::Kill(childPid, SIGTERM);
+    return false;
+  }
+
+  size_t num_bytes;
+  error = socket_pipe.WriteWithTimeout(&protocol_info, sizeof(protocol_info),
+                                       std::chrono::seconds(2), num_bytes);
+  if (error.Fail()) {
+    LLDB_LOGF(log,
+              "lldb-platform parent: "
+              "socket_pipe.WriteWithTimeout(WSAPROTOCOL_INFO) failed: %s",
+              error.AsCString());
+    Host::Kill(childPid, SIGTERM);
+    return false;
+  }
+  if (num_bytes != sizeof(protocol_info)) {
+    LLDB_LOGF(log,
+              "lldb-platform parent: "
+              "socket_pipe.WriteWithTimeout(WSAPROTOCOL_INFO) failed: %d bytes",
+              num_bytes);
+    Host::Kill(childPid, SIGTERM);
+    return false;
+  }
+
+  socket_pipe.Close();
+
+  return true;
+}
+
+static bool SpawnProcessChild(pipe_t accept_fd,
+                              const std::string &listen_host_port,
+                              uint16_t port_offset,
+                              const lldb_private::Args &args) {
+  if (accept_fd == INVALID_HANDLE_VALUE)
+    return false;
+
+  Log *log = GetLog(LLDBLog::Platform);
+  if (!listen_host_port.empty()) {
+    LLDB_LOGF(log, "lldb-platform child: "
+                   "ambiguous parameters --listen and --accept");
+    exit(SOCKET_ERROR);
+  }
+
+  Pipe socket_pipe(accept_fd, LLDB_INVALID_PIPE);
+
+  WSAPROTOCOL_INFO protocol_info;
+  size_t num_bytes;
+  Status error =
+      socket_pipe.ReadWithTimeout(&protocol_info, sizeof(protocol_info),
+                                  std::chrono::seconds(2), num_bytes);
+  if (error.Fail()) {
+    LLDB_LOGF(log,
+              "lldb-platform child: "
+              "socket_pipe(0x%x).ReadWithTimeout(WSAPROTOCOL_INFO) failed: %s",
+              accept_fd, error.AsCString());
+    exit(SOCKET_ERROR);
+  }
+  if (num_bytes != sizeof(protocol_info)) {
+    LLDB_LOGF(log,
+              "lldb-platform child: "
+              "socket_pipe(0x%x).ReadWithTimeout(WSAPROTOCOL_INFO) failed: "
+              "%d bytes",
+              num_bytes);
+    exit(SOCKET_ERROR);
+  }
+
+  NativeSocket socket = ::WSASocket(FROM_PROTOCOL_INFO, FROM_PROTOCOL_INFO,
+                                    FROM_PROTOCOL_INFO, &protocol_info, 0, 0);
+  if (socket == INVALID_SOCKET) {
+    LLDB_LOGF(log,
+              "lldb-platform child: "
+              "WSASocket(FROM_PROTOCOL_INFO) failed: error %d",
+              ::WSAGetLastError());
+    exit(SOCKET_ERROR);
+  }
+
+  Connection *conn =
+      new ConnectionFileDescriptor(new TCPSocket(socket, true, false));
+  GDBRemoteCommunicationServerPlatform platform(Socket::ProtocolTcp, "tcp");
+  if (port_offset > 0)
+    platform.SetPortOffset(port_offset);
+  platform.SetPortMap(std::move(gdbserver_portmap));
+  platform.SetConnection(std::unique_ptr<Connection>(conn));
+  platform.Proc(args);
+  return true;
+}
+#endif
+
 // main
 int main_platform(int argc, char *argv[]) {
   const char *progname = argv[0];
@@ -123,6 +341,8 @@ int main_platform(int argc, char *argv[]) {
 #if !defined(_WIN32)
   signal(SIGPIPE, SIG_IGN);
   signal(SIGHUP, signal_handler);
+#else
+  pipe_t accept_fd = INVALID_HANDLE_VALUE;
 #endif
   int long_option_index = 0;
   Status error;
@@ -133,7 +353,6 @@ int main_platform(int argc, char *argv[]) {
   StringRef
       log_channels; // e.g. "lldb process threads:gdb-remote default:linux all"
 
-  GDBRemoteCommunicationServerPlatform::PortMap gdbserver_portmap;
   int min_gdbserver_port = 0;
   int max_gdbserver_port = 0;
   uint16_t port_offset = 0;
@@ -217,6 +436,17 @@ int main_platform(int argc, char *argv[]) {
         max_gdbserver_port = portnum;
     } break;
 
+#if defined(_WIN32)
+    case 'a': {
+      uint64_t fd;
+      if (!llvm::to_integer(optarg, fd)) {
+        WithColor::error() << "invalid accept fd " << optarg << "\n";
+        option_error = 6;
+      }
+      accept_fd = (pipe_t)fd;
+    } break;
+#endif
+
     case 'h': /* fall-through is intentional */
     case '?':
       show_usage = true;
@@ -240,7 +470,11 @@ int main_platform(int argc, char *argv[]) {
   }
 
   // Print usage and exit if no listening port is specified.
+#if !defined(_WIN32)
   if (listen_host_port.empty())
+#else
+  if (listen_host_port.empty() && accept_fd == INVALID_HANDLE_VALUE)
+#endif
     show_usage = true;
 
   if (show_usage || option_error) {
@@ -254,6 +488,13 @@ int main_platform(int argc, char *argv[]) {
   lldb_private::Args inferior_arguments;
   inferior_arguments.SetArguments(argc, const_cast<const char **>(argv));
 
+#if defined(_WIN32)
+  // Child process will handle the connection and exit.
+  if (SpawnProcessChild(accept_fd, listen_host_port, port_offset,
+                        inferior_arguments))
+    return 0;
+#endif
+
   const bool children_inherit_listen_socket = false;
   // the test suite makes many connections in parallel, let's not miss any.
   // The highest this should get reasonably is a function of the number
@@ -303,32 +544,39 @@ int main_platform(int argc, char *argv[]) {
       ::pid_t waitResult;
       while ((waitResult = waitpid(-1, nullptr, WNOHANG)) > 0) {
         // waitResult is the child pid
+        std::lock_guard<std::mutex> guard(gdbserver_portmap_mutex);
         gdbserver_portmap.FreePortForProcess(waitResult);
       }
 #endif
-      // TODO: Clean up portmap for Windows when children die
-      // See https://github.com/llvm/llvm-project/issues/90923
-
       // After collecting zombie ports, get the next available
-      GDBRemoteCommunicationServerPlatform::PortMap portmap_for_child;
-      llvm::Expected<uint16_t> available_port =
-          gdbserver_portmap.GetNextAvailablePort();
-      if (available_port) {
-        // GetNextAvailablePort() may return 0 if gdbserver_portmap is empty.
-        if (*available_port)
-          portmap_for_child.AllowPort(*available_port);
-      } else {
-        llvm::consumeError(available_port.takeError());
+      std::optional<uint16_t> available_port;
+      {
+        std::lock_guard<std::mutex> guard(gdbserver_portmap_mutex);
+        auto port = gdbserver_portmap.GetNextAvailablePort();
+        if (port)
+          available_port = *port;
+        else
+          llvm::consumeError(port.takeError());
+      }
+      if (!available_port) {
         fprintf(stderr,
                 "no available gdbserver port for connection - dropping...\n");
         delete conn;
         continue;
       }
+#if !defined(_WIN32)
+      GDBRemoteCommunicationServerPlatform::PortMap portmap_for_child;
+      // GetNextAvailablePort() may return 0 if gdbserver_portmap is empty.
+      if (*available_port)
+        portmap_for_child.AllowPort(*available_port);
       platform.SetPortMap(std::move(portmap_for_child));
 
       auto childPid = fork();
       if (childPid) {
-        gdbserver_portmap.AssociatePortWithProcess(*available_port, childPid);
+        {
+          std::lock_guard<std::mutex> guard(gdbserver_portmap_mutex);
+          gdbserver_portmap.AssociatePortWithProcess(*available_port, childPid);
+        }
         // Parent doesn't need a connection to the lldb client
         delete conn;
 
@@ -340,6 +588,18 @@ int main_platform(int argc, char *argv[]) {
         // Listening socket is owned by parent process.
         acceptor_up.release();
       }
+#else
+      if (!SpawnProcessParent(progname, conn, *available_port, port_offset,
+                              inferior_arguments, log_file, log_channels)) {
+        std::lock_guard<std::mutex> guard(gdbserver_portmap_mutex);
+        gdbserver_portmap.FreePort(*available_port);
+      }
+      // Parent doesn't need a connection to the lldb client
+      delete conn;
+
+      // Parent will continue to listen for new connections.
+      continue;
+#endif
     } else {
       // If not running as a server, this process will not accept
       // connections while a connection is active.
@@ -350,33 +610,7 @@ int main_platform(int argc, char *argv[]) {
     }
 
     platform.SetConnection(std::unique_ptr<Connection>(conn));
-
-    if (platform.IsConnected()) {
-      if (inferior_arguments.GetArgumentCount() > 0) {
-        lldb::pid_t pid = LLDB_INVALID_PROCESS_ID;
-        std::optional<uint16_t> port;
-        std::string socket_name;
-        Status error = platform.LaunchGDBServer(inferior_arguments,
-                                                "", // hostname
-                                                pid, port, socket_name);
-        if (error.Success())
-          platform.SetPendingGdbServer(pid, *port, socket_name);
-        else
-          fprintf(stderr, "failed to start gdbserver: %s\n", error.AsCString());
-      }
-
-      bool interrupt = false;
-      bool done = false;
-      while (!interrupt && !done) {
-        if (platform.GetPacketAndSendResponse(std::nullopt, error, interrupt,
-                                              done) !=
-            GDBRemoteCommunication::PacketResult::Success)
-          break;
-      }
-
-      if (error.Fail())
-        WithColor::error() << error.AsCString() << '\n';
-    }
+    platform.Proc(inferior_arguments);
   } while (g_server);
 
   fprintf(stderr, "lldb-server exiting...\n");



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