1 //===-- DebuggerThread.cpp --------------------------------------*- C++ -*-===//
2 //
3 //                     The LLVM Compiler Infrastructure
4 //
5 // This file is distributed under the University of Illinois Open Source
6 // License. See LICENSE.TXT for details.
7 //
8 //===----------------------------------------------------------------------===//
9 
10 #include "DebuggerThread.h"
11 #include "ExceptionRecord.h"
12 #include "IDebugDelegate.h"
13 
14 #include "lldb/Core/ModuleSpec.h"
15 #include "lldb/Host/Predicate.h"
16 #include "lldb/Host/ThreadLauncher.h"
17 #include "lldb/Host/windows/HostProcessWindows.h"
18 #include "lldb/Host/windows/HostThreadWindows.h"
19 #include "lldb/Host/windows/ProcessLauncherWindows.h"
20 #include "lldb/Target/Process.h"
21 #include "lldb/Target/ProcessLaunchInfo.h"
22 #include "lldb/Utility/FileSpec.h"
23 #include "lldb/Utility/Log.h"
24 #include "lldb/Utility/Status.h"
25 
26 #include "Plugins/Process/Windows/Common/ProcessWindowsLog.h"
27 
28 #include "llvm/ADT/STLExtras.h"
29 #include "llvm/Support/ConvertUTF.h"
30 #include "llvm/Support/Threading.h"
31 #include "llvm/Support/raw_ostream.h"
32 
33 using namespace lldb;
34 using namespace lldb_private;
35 
36 namespace {
37 struct DebugLaunchContext {
38   DebugLaunchContext(DebuggerThread *thread,
39                      const ProcessLaunchInfo &launch_info)
40       : m_thread(thread), m_launch_info(launch_info) {}
41   DebuggerThread *m_thread;
42   ProcessLaunchInfo m_launch_info;
43 };
44 
45 struct DebugAttachContext {
46   DebugAttachContext(DebuggerThread *thread, lldb::pid_t pid,
47                      const ProcessAttachInfo &attach_info)
48       : m_thread(thread), m_pid(pid), m_attach_info(attach_info) {}
49   DebuggerThread *m_thread;
50   lldb::pid_t m_pid;
51   ProcessAttachInfo m_attach_info;
52 };
53 }
54 
55 DebuggerThread::DebuggerThread(DebugDelegateSP debug_delegate)
56     : m_debug_delegate(debug_delegate), m_pid_to_detach(0),
57       m_is_shutting_down(false) {
58   m_debugging_ended_event = ::CreateEvent(nullptr, TRUE, FALSE, nullptr);
59 }
60 
61 DebuggerThread::~DebuggerThread() { ::CloseHandle(m_debugging_ended_event); }
62 
63 Status DebuggerThread::DebugLaunch(const ProcessLaunchInfo &launch_info) {
64   Log *log = ProcessWindowsLog::GetLogIfAny(WINDOWS_LOG_PROCESS);
65   LLDB_LOG(log, "launching '{0}'", launch_info.GetExecutableFile().GetPath());
66 
67   Status error;
68   DebugLaunchContext *context = new DebugLaunchContext(this, launch_info);
69   HostThread slave_thread(ThreadLauncher::LaunchThread(
70       "lldb.plugin.process-windows.slave[?]", DebuggerThreadLaunchRoutine,
71       context, &error));
72 
73   if (!error.Success())
74     LLDB_LOG(log, "couldn't launch debugger thread. {0}", error);
75 
76   return error;
77 }
78 
79 Status DebuggerThread::DebugAttach(lldb::pid_t pid,
80                                    const ProcessAttachInfo &attach_info) {
81   Log *log = ProcessWindowsLog::GetLogIfAny(WINDOWS_LOG_PROCESS);
82   LLDB_LOG(log, "attaching to '{0}'", pid);
83 
84   Status error;
85   DebugAttachContext *context = new DebugAttachContext(this, pid, attach_info);
86   HostThread slave_thread(ThreadLauncher::LaunchThread(
87       "lldb.plugin.process-windows.slave[?]", DebuggerThreadAttachRoutine,
88       context, &error));
89 
90   if (!error.Success())
91     LLDB_LOG(log, "couldn't attach to process '{0}'. {1}", pid, error);
92 
93   return error;
94 }
95 
96 lldb::thread_result_t DebuggerThread::DebuggerThreadLaunchRoutine(void *data) {
97   DebugLaunchContext *context = static_cast<DebugLaunchContext *>(data);
98   lldb::thread_result_t result =
99       context->m_thread->DebuggerThreadLaunchRoutine(context->m_launch_info);
100   delete context;
101   return result;
102 }
103 
104 lldb::thread_result_t DebuggerThread::DebuggerThreadAttachRoutine(void *data) {
105   DebugAttachContext *context = static_cast<DebugAttachContext *>(data);
106   lldb::thread_result_t result = context->m_thread->DebuggerThreadAttachRoutine(
107       context->m_pid, context->m_attach_info);
108   delete context;
109   return result;
110 }
111 
112 lldb::thread_result_t DebuggerThread::DebuggerThreadLaunchRoutine(
113     const ProcessLaunchInfo &launch_info) {
114   // Grab a shared_ptr reference to this so that we know it won't get deleted
115   // until after the thread routine has exited.
116   std::shared_ptr<DebuggerThread> this_ref(shared_from_this());
117 
118   Log *log = ProcessWindowsLog::GetLogIfAny(WINDOWS_LOG_PROCESS);
119   LLDB_LOG(log, "preparing to launch '{0}' on background thread.",
120            launch_info.GetExecutableFile().GetPath());
121 
122   Status error;
123   ProcessLauncherWindows launcher;
124   HostProcess process(launcher.LaunchProcess(launch_info, error));
125   // If we couldn't create the process, notify waiters immediately.  Otherwise
126   // enter the debug loop and wait until we get the create process debug
127   // notification.  Note that if the process was created successfully, we can
128   // throw away the process handle we got from CreateProcess because Windows
129   // will give us another (potentially more useful?) handle when it sends us
130   // the CREATE_PROCESS_DEBUG_EVENT.
131   if (error.Success())
132     DebugLoop();
133   else
134     m_debug_delegate->OnDebuggerError(error, 0);
135 
136   return 0;
137 }
138 
139 lldb::thread_result_t DebuggerThread::DebuggerThreadAttachRoutine(
140     lldb::pid_t pid, const ProcessAttachInfo &attach_info) {
141   // Grab a shared_ptr reference to this so that we know it won't get deleted
142   // until after the thread routine has exited.
143   std::shared_ptr<DebuggerThread> this_ref(shared_from_this());
144 
145   Log *log = ProcessWindowsLog::GetLogIfAny(WINDOWS_LOG_PROCESS);
146   LLDB_LOG(log, "preparing to attach to process '{0}' on background thread.",
147            pid);
148 
149   if (!DebugActiveProcess((DWORD)pid)) {
150     Status error(::GetLastError(), eErrorTypeWin32);
151     m_debug_delegate->OnDebuggerError(error, 0);
152     return 0;
153   }
154 
155   // The attach was successful, enter the debug loop.  From here on out, this
156   // is no different than a create process operation, so all the same comments
157   // in DebugLaunch should apply from this point out.
158   DebugLoop();
159 
160   return 0;
161 }
162 
163 Status DebuggerThread::StopDebugging(bool terminate) {
164   Status error;
165 
166   lldb::pid_t pid = m_process.GetProcessId();
167 
168   Log *log = ProcessWindowsLog::GetLogIfAny(WINDOWS_LOG_PROCESS);
169   LLDB_LOG(log, "terminate = {0}, inferior={1}.", terminate, pid);
170 
171   // Set m_is_shutting_down to true if it was false.  Return if it was already
172   // true.
173   bool expected = false;
174   if (!m_is_shutting_down.compare_exchange_strong(expected, true))
175     return error;
176 
177   // Make a copy of the process, since the termination sequence will reset
178   // DebuggerThread's internal copy and it needs to remain open for the Wait
179   // operation.
180   HostProcess process_copy = m_process;
181   lldb::process_t handle = m_process.GetNativeProcess().GetSystemHandle();
182 
183   if (terminate) {
184     // Initiate the termination before continuing the exception, so that the
185     // next debug event we get is the exit process event, and not some other
186     // event.
187     BOOL terminate_suceeded = TerminateProcess(handle, 0);
188     LLDB_LOG(log,
189              "calling TerminateProcess({0}, 0) (inferior={1}), success={2}",
190              handle, pid, terminate_suceeded);
191   }
192 
193   // If we're stuck waiting for an exception to continue (e.g. the user is at a
194   // breakpoint messing around in the debugger), continue it now.  But only
195   // AFTER calling TerminateProcess to make sure that the very next call to
196   // WaitForDebugEvent is an exit process event.
197   if (m_active_exception.get()) {
198     LLDB_LOG(log, "masking active exception");
199     ContinueAsyncException(ExceptionResult::MaskException);
200   }
201 
202   if (!terminate) {
203     // Indicate that we want to detach.
204     m_pid_to_detach = GetProcess().GetProcessId();
205 
206     // Force a fresh break so that the detach can happen from the debugger
207     // thread.
208     if (!::DebugBreakProcess(
209             GetProcess().GetNativeProcess().GetSystemHandle())) {
210       error.SetError(::GetLastError(), eErrorTypeWin32);
211     }
212   }
213 
214   LLDB_LOG(log, "waiting for detach from process {0} to complete.", pid);
215 
216   DWORD wait_result = WaitForSingleObject(m_debugging_ended_event, 5000);
217   if (wait_result != WAIT_OBJECT_0) {
218     error.SetError(GetLastError(), eErrorTypeWin32);
219     LLDB_LOG(log, "error: WaitForSingleObject({0}, 5000) returned {1}",
220              m_debugging_ended_event, wait_result);
221   } else
222     LLDB_LOG(log, "detach from process {0} completed successfully.", pid);
223 
224   if (!error.Success()) {
225     LLDB_LOG(log, "encountered an error while trying to stop process {0}. {1}",
226              pid, error);
227   }
228   return error;
229 }
230 
231 void DebuggerThread::ContinueAsyncException(ExceptionResult result) {
232   if (!m_active_exception.get())
233     return;
234 
235   Log *log = ProcessWindowsLog::GetLogIfAny(WINDOWS_LOG_PROCESS |
236                                             WINDOWS_LOG_EXCEPTION);
237   LLDB_LOG(log, "broadcasting for inferior process {0}.",
238            m_process.GetProcessId());
239 
240   m_active_exception.reset();
241   m_exception_pred.SetValue(result, eBroadcastAlways);
242 }
243 
244 void DebuggerThread::FreeProcessHandles() {
245   m_process = HostProcess();
246   m_main_thread = HostThread();
247   if (m_image_file) {
248     ::CloseHandle(m_image_file);
249     m_image_file = nullptr;
250   }
251 }
252 
253 void DebuggerThread::DebugLoop() {
254   Log *log = ProcessWindowsLog::GetLogIfAny(WINDOWS_LOG_EVENT);
255   DEBUG_EVENT dbe = {};
256   bool should_debug = true;
257   LLDB_LOGV(log, "Entering WaitForDebugEvent loop");
258   while (should_debug) {
259     LLDB_LOGV(log, "Calling WaitForDebugEvent");
260     BOOL wait_result = WaitForDebugEvent(&dbe, INFINITE);
261     if (wait_result) {
262       DWORD continue_status = DBG_CONTINUE;
263       switch (dbe.dwDebugEventCode) {
264       case EXCEPTION_DEBUG_EVENT: {
265         ExceptionResult status =
266             HandleExceptionEvent(dbe.u.Exception, dbe.dwThreadId);
267 
268         if (status == ExceptionResult::MaskException)
269           continue_status = DBG_CONTINUE;
270         else if (status == ExceptionResult::SendToApplication)
271           continue_status = DBG_EXCEPTION_NOT_HANDLED;
272 
273         break;
274       }
275       case CREATE_THREAD_DEBUG_EVENT:
276         continue_status =
277             HandleCreateThreadEvent(dbe.u.CreateThread, dbe.dwThreadId);
278         break;
279       case CREATE_PROCESS_DEBUG_EVENT:
280         continue_status =
281             HandleCreateProcessEvent(dbe.u.CreateProcessInfo, dbe.dwThreadId);
282         break;
283       case EXIT_THREAD_DEBUG_EVENT:
284         continue_status =
285             HandleExitThreadEvent(dbe.u.ExitThread, dbe.dwThreadId);
286         break;
287       case EXIT_PROCESS_DEBUG_EVENT:
288         continue_status =
289             HandleExitProcessEvent(dbe.u.ExitProcess, dbe.dwThreadId);
290         should_debug = false;
291         break;
292       case LOAD_DLL_DEBUG_EVENT:
293         continue_status = HandleLoadDllEvent(dbe.u.LoadDll, dbe.dwThreadId);
294         break;
295       case UNLOAD_DLL_DEBUG_EVENT:
296         continue_status = HandleUnloadDllEvent(dbe.u.UnloadDll, dbe.dwThreadId);
297         break;
298       case OUTPUT_DEBUG_STRING_EVENT:
299         continue_status = HandleODSEvent(dbe.u.DebugString, dbe.dwThreadId);
300         break;
301       case RIP_EVENT:
302         continue_status = HandleRipEvent(dbe.u.RipInfo, dbe.dwThreadId);
303         if (dbe.u.RipInfo.dwType == SLE_ERROR)
304           should_debug = false;
305         break;
306       }
307 
308       LLDB_LOGV(log, "calling ContinueDebugEvent({0}, {1}, {2}) on thread {3}.",
309                 dbe.dwProcessId, dbe.dwThreadId, continue_status,
310                 ::GetCurrentThreadId());
311 
312       ::ContinueDebugEvent(dbe.dwProcessId, dbe.dwThreadId, continue_status);
313 
314       if (m_detached) {
315         should_debug = false;
316       }
317     } else {
318       LLDB_LOG(log, "returned FALSE from WaitForDebugEvent.  Error = {0}",
319                ::GetLastError());
320 
321       should_debug = false;
322     }
323   }
324   FreeProcessHandles();
325 
326   LLDB_LOG(log, "WaitForDebugEvent loop completed, exiting.");
327   SetEvent(m_debugging_ended_event);
328 }
329 
330 ExceptionResult
331 DebuggerThread::HandleExceptionEvent(const EXCEPTION_DEBUG_INFO &info,
332                                      DWORD thread_id) {
333   Log *log =
334       ProcessWindowsLog::GetLogIfAny(WINDOWS_LOG_EVENT | WINDOWS_LOG_EXCEPTION);
335   if (m_is_shutting_down) {
336     // A breakpoint that occurs while `m_pid_to_detach` is non-zero is a magic
337     // exception that
338     // we use simply to wake up the DebuggerThread so that we can close out the
339     // debug loop.
340     if (m_pid_to_detach != 0 &&
341         info.ExceptionRecord.ExceptionCode == EXCEPTION_BREAKPOINT) {
342       LLDB_LOG(log, "Breakpoint exception is cue to detach from process {0:x}",
343                m_pid_to_detach.load());
344       ::DebugActiveProcessStop(m_pid_to_detach);
345       m_detached = true;
346     }
347 
348     // Don't perform any blocking operations while we're shutting down.  That
349     // will cause TerminateProcess -> WaitForSingleObject to time out.
350     return ExceptionResult::SendToApplication;
351   }
352 
353   bool first_chance = (info.dwFirstChance != 0);
354 
355   m_active_exception.reset(
356       new ExceptionRecord(info.ExceptionRecord, thread_id));
357   LLDB_LOG(log, "encountered {0} chance exception {1:x} on thread {2:x}",
358            first_chance ? "first" : "second",
359            info.ExceptionRecord.ExceptionCode, thread_id);
360 
361   ExceptionResult result =
362       m_debug_delegate->OnDebugException(first_chance, *m_active_exception);
363   m_exception_pred.SetValue(result, eBroadcastNever);
364 
365   LLDB_LOG(log, "waiting for ExceptionPred != BreakInDebugger");
366   result = *m_exception_pred.WaitForValueNotEqualTo(
367       ExceptionResult::BreakInDebugger);
368 
369   LLDB_LOG(log, "got ExceptionPred = {0}", (int)m_exception_pred.GetValue());
370   return result;
371 }
372 
373 DWORD
374 DebuggerThread::HandleCreateThreadEvent(const CREATE_THREAD_DEBUG_INFO &info,
375                                         DWORD thread_id) {
376   Log *log =
377       ProcessWindowsLog::GetLogIfAny(WINDOWS_LOG_EVENT | WINDOWS_LOG_THREAD);
378   LLDB_LOG(log, "Thread {0:x} spawned in process {1}", thread_id,
379            m_process.GetProcessId());
380   HostThread thread(info.hThread);
381   thread.GetNativeThread().SetOwnsHandle(false);
382   m_debug_delegate->OnCreateThread(thread);
383   return DBG_CONTINUE;
384 }
385 
386 DWORD
387 DebuggerThread::HandleCreateProcessEvent(const CREATE_PROCESS_DEBUG_INFO &info,
388                                          DWORD thread_id) {
389   Log *log =
390       ProcessWindowsLog::GetLogIfAny(WINDOWS_LOG_EVENT | WINDOWS_LOG_PROCESS);
391   uint32_t process_id = ::GetProcessId(info.hProcess);
392 
393   LLDB_LOG(log, "process {0} spawned", process_id);
394 
395   std::string thread_name;
396   llvm::raw_string_ostream name_stream(thread_name);
397   name_stream << "lldb.plugin.process-windows.slave[" << process_id << "]";
398   name_stream.flush();
399   llvm::set_thread_name(thread_name);
400 
401   // info.hProcess and info.hThread are closed automatically by Windows when
402   // EXIT_PROCESS_DEBUG_EVENT is received.
403   m_process = HostProcess(info.hProcess);
404   ((HostProcessWindows &)m_process.GetNativeProcess()).SetOwnsHandle(false);
405   m_main_thread = HostThread(info.hThread);
406   m_main_thread.GetNativeThread().SetOwnsHandle(false);
407   m_image_file = info.hFile;
408 
409   lldb::addr_t load_addr = reinterpret_cast<lldb::addr_t>(info.lpBaseOfImage);
410   m_debug_delegate->OnDebuggerConnected(load_addr);
411 
412   return DBG_CONTINUE;
413 }
414 
415 DWORD
416 DebuggerThread::HandleExitThreadEvent(const EXIT_THREAD_DEBUG_INFO &info,
417                                       DWORD thread_id) {
418   Log *log =
419       ProcessWindowsLog::GetLogIfAny(WINDOWS_LOG_EVENT | WINDOWS_LOG_THREAD);
420   LLDB_LOG(log, "Thread {0} exited with code {1} in process {2}", thread_id,
421            info.dwExitCode, m_process.GetProcessId());
422   m_debug_delegate->OnExitThread(thread_id, info.dwExitCode);
423   return DBG_CONTINUE;
424 }
425 
426 DWORD
427 DebuggerThread::HandleExitProcessEvent(const EXIT_PROCESS_DEBUG_INFO &info,
428                                        DWORD thread_id) {
429   Log *log =
430       ProcessWindowsLog::GetLogIfAny(WINDOWS_LOG_EVENT | WINDOWS_LOG_THREAD);
431   LLDB_LOG(log, "process {0} exited with code {1}", m_process.GetProcessId(),
432            info.dwExitCode);
433 
434   m_debug_delegate->OnExitProcess(info.dwExitCode);
435 
436   FreeProcessHandles();
437   return DBG_CONTINUE;
438 }
439 
440 DWORD
441 DebuggerThread::HandleLoadDllEvent(const LOAD_DLL_DEBUG_INFO &info,
442                                    DWORD thread_id) {
443   Log *log = ProcessWindowsLog::GetLogIfAny(WINDOWS_LOG_EVENT);
444   if (info.hFile == nullptr) {
445     // Not sure what this is, so just ignore it.
446     LLDB_LOG(log, "Warning: Inferior {0} has a NULL file handle, returning...",
447              m_process.GetProcessId());
448     return DBG_CONTINUE;
449   }
450 
451   std::vector<wchar_t> buffer(1);
452   DWORD required_size =
453       GetFinalPathNameByHandleW(info.hFile, &buffer[0], 0, VOLUME_NAME_DOS);
454   if (required_size > 0) {
455     buffer.resize(required_size + 1);
456     required_size = GetFinalPathNameByHandleW(info.hFile, &buffer[0],
457                                               required_size, VOLUME_NAME_DOS);
458     std::string path_str_utf8;
459     llvm::convertWideToUTF8(buffer.data(), path_str_utf8);
460     llvm::StringRef path_str = path_str_utf8;
461     const char *path = path_str.data();
462     if (path_str.startswith("\\\\?\\"))
463       path += 4;
464 
465     FileSpec file_spec(path, false);
466     ModuleSpec module_spec(file_spec);
467     lldb::addr_t load_addr = reinterpret_cast<lldb::addr_t>(info.lpBaseOfDll);
468 
469     LLDB_LOG(log, "Inferior {0} - DLL '{1}' loaded at address {2:x}...",
470              m_process.GetProcessId(), path, info.lpBaseOfDll);
471 
472     m_debug_delegate->OnLoadDll(module_spec, load_addr);
473   } else {
474     LLDB_LOG(
475         log,
476         "Inferior {0} - Error {1} occurred calling GetFinalPathNameByHandle",
477         m_process.GetProcessId(), ::GetLastError());
478   }
479   // Windows does not automatically close info.hFile, so we need to do it.
480   ::CloseHandle(info.hFile);
481   return DBG_CONTINUE;
482 }
483 
484 DWORD
485 DebuggerThread::HandleUnloadDllEvent(const UNLOAD_DLL_DEBUG_INFO &info,
486                                      DWORD thread_id) {
487   Log *log = ProcessWindowsLog::GetLogIfAny(WINDOWS_LOG_EVENT);
488   LLDB_LOG(log, "process {0} unloading DLL at addr {1:x}.",
489            m_process.GetProcessId(), info.lpBaseOfDll);
490 
491   m_debug_delegate->OnUnloadDll(
492       reinterpret_cast<lldb::addr_t>(info.lpBaseOfDll));
493   return DBG_CONTINUE;
494 }
495 
496 DWORD
497 DebuggerThread::HandleODSEvent(const OUTPUT_DEBUG_STRING_INFO &info,
498                                DWORD thread_id) {
499   return DBG_CONTINUE;
500 }
501 
502 DWORD
503 DebuggerThread::HandleRipEvent(const RIP_INFO &info, DWORD thread_id) {
504   Log *log = ProcessWindowsLog::GetLogIfAny(WINDOWS_LOG_EVENT);
505   LLDB_LOG(log, "encountered error {0} (type={1}) in process {2} thread {3}",
506            info.dwError, info.dwType, m_process.GetProcessId(), thread_id);
507 
508   Status error(info.dwError, eErrorTypeWin32);
509   m_debug_delegate->OnDebuggerError(error, info.dwType);
510 
511   return DBG_CONTINUE;
512 }
513