//===-- DebuggerThread.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 "DebuggerThread.h"
#include "ExceptionRecord.h"
#include "IDebugDelegate.h"
#include "lldb/Core/ModuleSpec.h"
#include "lldb/Host/ProcessLaunchInfo.h"
#include "lldb/Host/ThreadLauncher.h"
#include "lldb/Host/windows/AutoHandle.h"
#include "lldb/Host/windows/HostProcessWindows.h"
#include "lldb/Host/windows/HostThreadWindows.h"
#include "lldb/Host/windows/ProcessLauncherWindows.h"
#include "lldb/Target/Process.h"
#include "lldb/Utility/FileSpec.h"
#include "lldb/Utility/Log.h"
#include "lldb/Utility/Predicate.h"
#include "lldb/Utility/Status.h"
#include "Plugins/Process/Windows/Common/ProcessWindowsLog.h"
#include "llvm/ADT/STLExtras.h"
#include "llvm/Support/ConvertUTF.h"
#include "llvm/Support/Threading.h"
#include "llvm/Support/raw_ostream.h"
#include <optional>
#include <psapi.h>
#ifndef STATUS_WX86_BREAKPOINT
#define STATUS_WX86_BREAKPOINT 0x4000001FL // For WOW64
#endif
using namespace lldb;
using namespace lldb_private;
DebuggerThread::DebuggerThread(DebugDelegateSP debug_delegate)
: m_debug_delegate(debug_delegate), m_pid_to_detach(0),
m_is_shutting_down(false) {
m_debugging_ended_event = ::CreateEvent(nullptr, TRUE, FALSE, nullptr);
}
DebuggerThread::~DebuggerThread() { ::CloseHandle(m_debugging_ended_event); }
Status DebuggerThread::DebugLaunch(const ProcessLaunchInfo &launch_info) {
Log *log = GetLog(WindowsLog::Process);
LLDB_LOG(log, "launching '{0}'", launch_info.GetExecutableFile().GetPath());
Status result;
llvm::Expected<HostThread> secondary_thread = ThreadLauncher::LaunchThread(
"lldb.plugin.process-windows.secondary[?]",
[this, launch_info] { return DebuggerThreadLaunchRoutine(launch_info); });
if (!secondary_thread) {
result = Status::FromError(secondary_thread.takeError());
LLDB_LOG(log, "couldn't launch debugger thread. {0}", result);
}
return result;
}
Status DebuggerThread::DebugAttach(lldb::pid_t pid,
const ProcessAttachInfo &attach_info) {
Log *log = GetLog(WindowsLog::Process);
LLDB_LOG(log, "attaching to '{0}'", pid);
Status result;
llvm::Expected<HostThread> secondary_thread = ThreadLauncher::LaunchThread(
"lldb.plugin.process-windows.secondary[?]", [this, pid, attach_info] {
return DebuggerThreadAttachRoutine(pid, attach_info);
});
if (!secondary_thread) {
result = Status::FromError(secondary_thread.takeError());
LLDB_LOG(log, "couldn't attach to process '{0}'. {1}", pid, result);
}
return result;
}
lldb::thread_result_t DebuggerThread::DebuggerThreadLaunchRoutine(
const ProcessLaunchInfo &launch_info) {
// Grab a shared_ptr reference to this so that we know it won't get deleted
// until after the thread routine has exited.
std::shared_ptr<DebuggerThread> this_ref(shared_from_this());
Log *log = GetLog(WindowsLog::Process);
LLDB_LOG(log, "preparing to launch '{0}' on background thread.",
launch_info.GetExecutableFile().GetPath());
Status error;
ProcessLauncherWindows launcher;
HostProcess process(launcher.LaunchProcess(launch_info, error));
// If we couldn't create the process, notify waiters immediately. Otherwise
// enter the debug loop and wait until we get the create process debug
// notification. Note that if the process was created successfully, we can
// throw away the process handle we got from CreateProcess because Windows
// will give us another (potentially more useful?) handle when it sends us
// the CREATE_PROCESS_DEBUG_EVENT.
if (error.Success())
DebugLoop();
else
m_debug_delegate->OnDebuggerError(error, 0);
return {};
}
lldb::thread_result_t DebuggerThread::DebuggerThreadAttachRoutine(
lldb::pid_t pid, const ProcessAttachInfo &attach_info) {
// Grab a shared_ptr reference to this so that we know it won't get deleted
// until after the thread routine has exited.
std::shared_ptr<DebuggerThread> this_ref(shared_from_this());
Log *log = GetLog(WindowsLog::Process);
LLDB_LOG(log, "preparing to attach to process '{0}' on background thread.",
pid);
if (!DebugActiveProcess((DWORD)pid)) {
Status error(::GetLastError(), eErrorTypeWin32);
m_debug_delegate->OnDebuggerError(error, 0);
return {};
}
// The attach was successful, enter the debug loop. From here on out, this
// is no different than a create process operation, so all the same comments
// in DebugLaunch should apply from this point out.
DebugLoop();
return {};
}
Status DebuggerThread::StopDebugging(bool terminate) {
Status error;
lldb::pid_t pid = m_process.GetProcessId();
Log *log = GetLog(WindowsLog::Process);
LLDB_LOG(log, "terminate = {0}, inferior={1}.", terminate, pid);
// Set m_is_shutting_down to true if it was false. Return if it was already
// true.
bool expected = false;
if (!m_is_shutting_down.compare_exchange_strong(expected, true))
return error;
// Make a copy of the process, since the termination sequence will reset
// DebuggerThread's internal copy and it needs to remain open for the Wait
// operation.
HostProcess process_copy = m_process;
lldb::process_t handle = m_process.GetNativeProcess().GetSystemHandle();
if (terminate) {
if (handle != nullptr && handle != LLDB_INVALID_PROCESS) {
// Initiate the termination before continuing the exception, so that the
// next debug event we get is the exit process event, and not some other
// event.
BOOL terminate_suceeded = TerminateProcess(handle, 0);
LLDB_LOG(log,
"calling TerminateProcess({0}, 0) (inferior={1}), success={2}",
handle, pid, terminate_suceeded);
} else {
LLDB_LOG(log,
"NOT calling TerminateProcess because the inferior is not valid "
"({0}, 0) (inferior={1})",
handle, pid);
}
}
// If we're stuck waiting for an exception to continue (e.g. the user is at a
// breakpoint messing around in the debugger), continue it now. But only
// AFTER calling TerminateProcess to make sure that the very next call to
// WaitForDebugEvent is an exit process event.
if (m_active_exception.get()) {
LLDB_LOG(log, "masking active exception");
ContinueAsyncException(ExceptionResult::MaskException);
}
if (!terminate) {
// Indicate that we want to detach.
m_pid_to_detach = GetProcess().GetProcessId();
// Force a fresh break so that the detach can happen from the debugger
// thread.
if (!::DebugBreakProcess(
GetProcess().GetNativeProcess().GetSystemHandle())) {
error = Status(::GetLastError(), eErrorTypeWin32);
}
}
LLDB_LOG(log, "waiting for detach from process {0} to complete.", pid);
DWORD wait_result = WaitForSingleObject(m_debugging_ended_event, 5000);
if (wait_result != WAIT_OBJECT_0) {
error = Status(GetLastError(), eErrorTypeWin32);
LLDB_LOG(log, "error: WaitForSingleObject({0}, 5000) returned {1}",
m_debugging_ended_event, wait_result);
} else
LLDB_LOG(log, "detach from process {0} completed successfully.", pid);
if (!error.Success()) {
LLDB_LOG(log, "encountered an error while trying to stop process {0}. {1}",
pid, error);
}
return error;
}
void DebuggerThread::ContinueAsyncException(ExceptionResult result) {
if (!m_active_exception.get())
return;
Log *log = GetLog(WindowsLog::Process | WindowsLog::Exception);
LLDB_LOG(log, "broadcasting for inferior process {0}.",
m_process.GetProcessId());
m_active_exception.reset();
m_exception_pred.SetValue(result, eBroadcastAlways);
}
void DebuggerThread::FreeProcessHandles() {
m_process = HostProcess();
m_main_thread = HostThread();
if (m_image_file) {
::CloseHandle(m_image_file);
m_image_file = nullptr;
}
}
void DebuggerThread::DebugLoop() {
Log *log = GetLog(WindowsLog::Event);
DEBUG_EVENT dbe = {};
bool should_debug = true;
LLDB_LOGV(log, "Entering WaitForDebugEvent loop");
while (should_debug) {
LLDB_LOGV(log, "Calling WaitForDebugEvent");
BOOL wait_result = WaitForDebugEvent(&dbe, INFINITE);
if (wait_result) {
DWORD continue_status = DBG_CONTINUE;
switch (dbe.dwDebugEventCode) {
default:
llvm_unreachable("Unhandle debug event code!");
case EXCEPTION_DEBUG_EVENT: {
ExceptionResult status =
HandleExceptionEvent(dbe.u.Exception, dbe.dwThreadId);
if (status == ExceptionResult::MaskException)
continue_status = DBG_CONTINUE;
else if (status == ExceptionResult::SendToApplication)
continue_status = DBG_EXCEPTION_NOT_HANDLED;
break;
}
case CREATE_THREAD_DEBUG_EVENT:
continue_status =
HandleCreateThreadEvent(dbe.u.CreateThread, dbe.dwThreadId);
break;
case CREATE_PROCESS_DEBUG_EVENT:
continue_status =
HandleCreateProcessEvent(dbe.u.CreateProcessInfo, dbe.dwThreadId);
break;
case EXIT_THREAD_DEBUG_EVENT:
continue_status =
HandleExitThreadEvent(dbe.u.ExitThread, dbe.dwThreadId);
break;
case EXIT_PROCESS_DEBUG_EVENT:
continue_status =
HandleExitProcessEvent(dbe.u.ExitProcess, dbe.dwThreadId);
should_debug = false;
break;
case LOAD_DLL_DEBUG_EVENT:
continue_status = HandleLoadDllEvent(dbe.u.LoadDll, dbe.dwThreadId);
break;
case UNLOAD_DLL_DEBUG_EVENT:
continue_status = HandleUnloadDllEvent(dbe.u.UnloadDll, dbe.dwThreadId);
break;
case OUTPUT_DEBUG_STRING_EVENT:
continue_status = HandleODSEvent(dbe.u.DebugString, dbe.dwThreadId);
break;
case RIP_EVENT:
continue_status = HandleRipEvent(dbe.u.RipInfo, dbe.dwThreadId);
if (dbe.u.RipInfo.dwType == SLE_ERROR)
should_debug = false;
break;
}
LLDB_LOGV(log, "calling ContinueDebugEvent({0}, {1}, {2}) on thread {3}.",
dbe.dwProcessId, dbe.dwThreadId, continue_status,
::GetCurrentThreadId());
::ContinueDebugEvent(dbe.dwProcessId, dbe.dwThreadId, continue_status);
if (m_detached) {
should_debug = false;
}
} else {
LLDB_LOG(log, "returned FALSE from WaitForDebugEvent. Error = {0}",
::GetLastError());
should_debug = false;
}
}
FreeProcessHandles();
LLDB_LOG(log, "WaitForDebugEvent loop completed, exiting.");
::SetEvent(m_debugging_ended_event);
}
ExceptionResult
DebuggerThread::HandleExceptionEvent(const EXCEPTION_DEBUG_INFO &info,
DWORD thread_id) {
Log *log = GetLog(WindowsLog::Event | WindowsLog::Exception);
if (m_is_shutting_down) {
// A breakpoint that occurs while `m_pid_to_detach` is non-zero is a magic
// exception that
// we use simply to wake up the DebuggerThread so that we can close out the
// debug loop.
if (m_pid_to_detach != 0 &&
(info.ExceptionRecord.ExceptionCode == EXCEPTION_BREAKPOINT ||
info.ExceptionRecord.ExceptionCode == STATUS_WX86_BREAKPOINT)) {
LLDB_LOG(log, "Breakpoint exception is cue to detach from process {0:x}",
m_pid_to_detach.load());
::DebugActiveProcessStop(m_pid_to_detach);
m_detached = true;
}
// Don't perform any blocking operations while we're shutting down. That
// will cause TerminateProcess -> WaitForSingleObject to time out.
return ExceptionResult::SendToApplication;
}
bool first_chance = (info.dwFirstChance != 0);
m_active_exception.reset(
new ExceptionRecord(info.ExceptionRecord, thread_id));
LLDB_LOG(log, "encountered {0} chance exception {1:x} on thread {2:x}",
first_chance ? "first" : "second",
info.ExceptionRecord.ExceptionCode, thread_id);
ExceptionResult result =
m_debug_delegate->OnDebugException(first_chance, *m_active_exception);
m_exception_pred.SetValue(result, eBroadcastNever);
LLDB_LOG(log, "waiting for ExceptionPred != BreakInDebugger");
result = *m_exception_pred.WaitForValueNotEqualTo(
ExceptionResult::BreakInDebugger);
LLDB_LOG(log, "got ExceptionPred = {0}", (int)m_exception_pred.GetValue());
return result;
}
DWORD
DebuggerThread::HandleCreateThreadEvent(const CREATE_THREAD_DEBUG_INFO &info,
DWORD thread_id) {
Log *log = GetLog(WindowsLog::Event | WindowsLog::Thread);
LLDB_LOG(log, "Thread {0} spawned in process {1}", thread_id,
m_process.GetProcessId());
HostThread thread(info.hThread);
thread.GetNativeThread().SetOwnsHandle(false);
m_debug_delegate->OnCreateThread(thread);
return DBG_CONTINUE;
}
DWORD
DebuggerThread::HandleCreateProcessEvent(const CREATE_PROCESS_DEBUG_INFO &info,
DWORD thread_id) {
Log *log = GetLog(WindowsLog::Event | WindowsLog::Process);
uint32_t process_id = ::GetProcessId(info.hProcess);
LLDB_LOG(log, "process {0} spawned", process_id);
std::string thread_name;
llvm::raw_string_ostream name_stream(thread_name);
name_stream << "lldb.plugin.process-windows.secondary[" << process_id << "]";
name_stream.flush();
llvm::set_thread_name(thread_name);
// info.hProcess and info.hThread are closed automatically by Windows when
// EXIT_PROCESS_DEBUG_EVENT is received.
m_process = HostProcess(info.hProcess);
((HostProcessWindows &)m_process.GetNativeProcess()).SetOwnsHandle(false);
m_main_thread = HostThread(info.hThread);
m_main_thread.GetNativeThread().SetOwnsHandle(false);
m_image_file = info.hFile;
lldb::addr_t load_addr = reinterpret_cast<lldb::addr_t>(info.lpBaseOfImage);
m_debug_delegate->OnDebuggerConnected(load_addr);
return DBG_CONTINUE;
}
DWORD
DebuggerThread::HandleExitThreadEvent(const EXIT_THREAD_DEBUG_INFO &info,
DWORD thread_id) {
Log *log = GetLog(WindowsLog::Event | WindowsLog::Thread);
LLDB_LOG(log, "Thread {0} exited with code {1} in process {2}", thread_id,
info.dwExitCode, m_process.GetProcessId());
m_debug_delegate->OnExitThread(thread_id, info.dwExitCode);
return DBG_CONTINUE;
}
DWORD
DebuggerThread::HandleExitProcessEvent(const EXIT_PROCESS_DEBUG_INFO &info,
DWORD thread_id) {
Log *log = GetLog(WindowsLog::Event | WindowsLog::Thread);
LLDB_LOG(log, "process {0} exited with code {1}", m_process.GetProcessId(),
info.dwExitCode);
m_debug_delegate->OnExitProcess(info.dwExitCode);
return DBG_CONTINUE;
}
static std::optional<std::string> GetFileNameFromHandleFallback(HANDLE hFile) {
// Check that file is not empty as we cannot map a file with zero length.
DWORD dwFileSizeHi = 0;
DWORD dwFileSizeLo = ::GetFileSize(hFile, &dwFileSizeHi);
if (dwFileSizeLo == 0 && dwFileSizeHi == 0)
return std::nullopt;
AutoHandle filemap(
::CreateFileMappingW(hFile, nullptr, PAGE_READONLY, 0, 1, NULL), nullptr);
if (!filemap.IsValid())
return std::nullopt;
auto view_deleter = [](void *pMem) { ::UnmapViewOfFile(pMem); };
std::unique_ptr<void, decltype(view_deleter)> pMem(
::MapViewOfFile(filemap.get(), FILE_MAP_READ, 0, 0, 1), view_deleter);
if (!pMem)
return std::nullopt;
std::array<wchar_t, MAX_PATH + 1> mapped_filename;
if (!::GetMappedFileNameW(::GetCurrentProcess(), pMem.get(),
mapped_filename.data(), mapped_filename.size()))
return std::nullopt;
// A series of null-terminated strings, plus an additional null character
std::array<wchar_t, 512> drive_strings;
drive_strings[0] = L'\0';
if (!::GetLogicalDriveStringsW(drive_strings.size(), drive_strings.data()))
return std::nullopt;
std::array<wchar_t, 3> drive = {L"_:"};
for (const wchar_t *it = drive_strings.data(); *it != L'\0';
it += wcslen(it) + 1) {
// Copy the drive letter to the template string
drive[0] = it[0];
std::array<wchar_t, MAX_PATH> device_name;
if (::QueryDosDeviceW(drive.data(), device_name.data(),
device_name.size())) {
size_t device_name_len = wcslen(device_name.data());
if (device_name_len < mapped_filename.size()) {
bool match = _wcsnicmp(mapped_filename.data(), device_name.data(),
device_name_len) == 0;
if (match && mapped_filename[device_name_len] == L'\\') {
// Replace device path with its drive letter
std::wstring rebuilt_path(drive.data());
rebuilt_path.append(&mapped_filename[device_name_len]);
std::string path_utf8;
llvm::convertWideToUTF8(rebuilt_path, path_utf8);
return path_utf8;
}
}
}
}
return std::nullopt;
}
DWORD
DebuggerThread::HandleLoadDllEvent(const LOAD_DLL_DEBUG_INFO &info,
DWORD thread_id) {
Log *log = GetLog(WindowsLog::Event);
if (info.hFile == nullptr) {
// Not sure what this is, so just ignore it.
LLDB_LOG(log, "Warning: Inferior {0} has a NULL file handle, returning...",
m_process.GetProcessId());
return DBG_CONTINUE;
}
auto on_load_dll = [&](llvm::StringRef path) {
FileSpec file_spec(path);
ModuleSpec module_spec(file_spec);
lldb::addr_t load_addr = reinterpret_cast<lldb::addr_t>(info.lpBaseOfDll);
LLDB_LOG(log, "Inferior {0} - DLL '{1}' loaded at address {2:x}...",
m_process.GetProcessId(), path, info.lpBaseOfDll);
m_debug_delegate->OnLoadDll(module_spec, load_addr);
};
std::vector<wchar_t> buffer(1);
DWORD required_size =
GetFinalPathNameByHandleW(info.hFile, &buffer[0], 0, VOLUME_NAME_DOS);
if (required_size > 0) {
buffer.resize(required_size + 1);
required_size = GetFinalPathNameByHandleW(info.hFile, &buffer[0],
required_size, VOLUME_NAME_DOS);
std::string path_str_utf8;
llvm::convertWideToUTF8(buffer.data(), path_str_utf8);
llvm::StringRef path_str = path_str_utf8;
const char *path = path_str.data();
if (path_str.starts_with("\\\\?\\"))
path += 4;
on_load_dll(path);
} else if (std::optional<std::string> path =
GetFileNameFromHandleFallback(info.hFile)) {
on_load_dll(*path);
} else {
LLDB_LOG(
log,
"Inferior {0} - Error {1} occurred calling GetFinalPathNameByHandle",
m_process.GetProcessId(), ::GetLastError());
}
// Windows does not automatically close info.hFile, so we need to do it.
::CloseHandle(info.hFile);
return DBG_CONTINUE;
}
DWORD
DebuggerThread::HandleUnloadDllEvent(const UNLOAD_DLL_DEBUG_INFO &info,
DWORD thread_id) {
Log *log = GetLog(WindowsLog::Event);
LLDB_LOG(log, "process {0} unloading DLL at addr {1:x}.",
m_process.GetProcessId(), info.lpBaseOfDll);
m_debug_delegate->OnUnloadDll(
reinterpret_cast<lldb::addr_t>(info.lpBaseOfDll));
return DBG_CONTINUE;
}
DWORD
DebuggerThread::HandleODSEvent(const OUTPUT_DEBUG_STRING_INFO &info,
DWORD thread_id) {
return DBG_CONTINUE;
}
DWORD
DebuggerThread::HandleRipEvent(const RIP_INFO &info, DWORD thread_id) {
Log *log = GetLog(WindowsLog::Event);
LLDB_LOG(log, "encountered error {0} (type={1}) in process {2} thread {3}",
info.dwError, info.dwType, m_process.GetProcessId(), thread_id);
Status error(info.dwError, eErrorTypeWin32);
m_debug_delegate->OnDebuggerError(error, info.dwType);
return DBG_CONTINUE;
}
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