1 //===-- SystemRuntimeMacOSX.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 
11 #include "lldb/Breakpoint/StoppointCallbackContext.h"
12 #include "lldb/Core/Log.h"
13 #include "lldb/Core/Module.h"
14 #include "lldb/Core/ModuleSpec.h"
15 #include "lldb/Core/PluginManager.h"
16 #include "lldb/Core/DataExtractor.h"
17 #include "lldb/Core/DataBufferHeap.h"
18 #include "lldb/Core/Section.h"
19 #include "lldb/Expression/ClangFunction.h"
20 #include "lldb/Expression/ClangUtilityFunction.h"
21 #include "lldb/Host/FileSpec.h"
22 #include "lldb/Symbol/ObjectFile.h"
23 #include "lldb/Symbol/SymbolContext.h"
24 #include "Plugins/Process/Utility/HistoryThread.h"
25 #include "lldb/Target/Queue.h"
26 #include "lldb/Target/QueueList.h"
27 #include "lldb/Target/Target.h"
28 #include "lldb/Target/Thread.h"
29 #include "lldb/Target/Process.h"
30 
31 
32 #include "SystemRuntimeMacOSX.h"
33 
34 using namespace lldb;
35 using namespace lldb_private;
36 
37 //----------------------------------------------------------------------
38 // Create an instance of this class. This function is filled into
39 // the plugin info class that gets handed out by the plugin factory and
40 // allows the lldb to instantiate an instance of this class.
41 //----------------------------------------------------------------------
42 SystemRuntime *
43 SystemRuntimeMacOSX::CreateInstance (Process* process)
44 {
45     bool create = false;
46     if (!create)
47     {
48         create = true;
49         Module* exe_module = process->GetTarget().GetExecutableModulePointer();
50         if (exe_module)
51         {
52             ObjectFile *object_file = exe_module->GetObjectFile();
53             if (object_file)
54             {
55                 create = (object_file->GetStrata() == ObjectFile::eStrataUser);
56             }
57         }
58 
59         if (create)
60         {
61             const llvm::Triple &triple_ref = process->GetTarget().GetArchitecture().GetTriple();
62             switch (triple_ref.getOS())
63             {
64                 case llvm::Triple::Darwin:
65                 case llvm::Triple::MacOSX:
66                 case llvm::Triple::IOS:
67                     create = triple_ref.getVendor() == llvm::Triple::Apple;
68                     break;
69                 default:
70                     create = false;
71                     break;
72             }
73         }
74     }
75 
76     if (create)
77         return new SystemRuntimeMacOSX (process);
78     return NULL;
79 }
80 
81 //----------------------------------------------------------------------
82 // Constructor
83 //----------------------------------------------------------------------
84 SystemRuntimeMacOSX::SystemRuntimeMacOSX (Process* process) :
85     SystemRuntime(process),
86     m_break_id(LLDB_INVALID_BREAK_ID),
87     m_mutex(Mutex::eMutexTypeRecursive),
88     m_get_queues_handler(process),
89     m_get_pending_items_handler(process),
90     m_get_item_info_handler(process),
91     m_get_thread_item_info_handler(process),
92     m_page_to_free(LLDB_INVALID_ADDRESS),
93     m_page_to_free_size(0),
94     m_lib_backtrace_recording_info(),
95     m_dispatch_queue_offsets_addr (LLDB_INVALID_ADDRESS),
96     m_libdispatch_offsets()
97 {
98 }
99 
100 //----------------------------------------------------------------------
101 // Destructor
102 //----------------------------------------------------------------------
103 SystemRuntimeMacOSX::~SystemRuntimeMacOSX()
104 {
105     Clear (true);
106 }
107 
108 void
109 SystemRuntimeMacOSX::Detach ()
110 {
111         m_get_queues_handler.Detach();
112         m_get_pending_items_handler.Detach();
113         m_get_item_info_handler.Detach();
114         m_get_thread_item_info_handler.Detach();
115 }
116 
117 //----------------------------------------------------------------------
118 // Clear out the state of this class.
119 //----------------------------------------------------------------------
120 void
121 SystemRuntimeMacOSX::Clear (bool clear_process)
122 {
123     Mutex::Locker locker(m_mutex);
124 
125     if (m_process->IsAlive() && LLDB_BREAK_ID_IS_VALID(m_break_id))
126         m_process->ClearBreakpointSiteByID(m_break_id);
127 
128     if (clear_process)
129         m_process = NULL;
130     m_break_id = LLDB_INVALID_BREAK_ID;
131 }
132 
133 
134 std::string
135 SystemRuntimeMacOSX::GetQueueNameFromThreadQAddress (addr_t dispatch_qaddr)
136 {
137     std::string dispatch_queue_name;
138     if (dispatch_qaddr == LLDB_INVALID_ADDRESS || dispatch_qaddr == 0)
139         return "";
140 
141     ReadLibdispatchOffsets ();
142     if (m_libdispatch_offsets.IsValid ())
143     {
144         // dispatch_qaddr is from a thread_info(THREAD_IDENTIFIER_INFO) call for a thread -
145         // deref it to get the address of the dispatch_queue_t structure for this thread's
146         // queue.
147         Error error;
148         addr_t dispatch_queue_addr = m_process->ReadPointerFromMemory (dispatch_qaddr, error);
149         if (error.Success())
150         {
151             if (m_libdispatch_offsets.dqo_version >= 4)
152             {
153                 // libdispatch versions 4+, pointer to dispatch name is in the
154                 // queue structure.
155                 addr_t pointer_to_label_address = dispatch_queue_addr + m_libdispatch_offsets.dqo_label;
156                 addr_t label_addr = m_process->ReadPointerFromMemory (pointer_to_label_address, error);
157                 if (error.Success())
158                 {
159                     m_process->ReadCStringFromMemory (label_addr, dispatch_queue_name, error);
160                 }
161             }
162             else
163             {
164                 // libdispatch versions 1-3, dispatch name is a fixed width char array
165                 // in the queue structure.
166                 addr_t label_addr = dispatch_queue_addr + m_libdispatch_offsets.dqo_label;
167                 dispatch_queue_name.resize (m_libdispatch_offsets.dqo_label_size, '\0');
168                 size_t bytes_read = m_process->ReadMemory (label_addr, &dispatch_queue_name[0], m_libdispatch_offsets.dqo_label_size, error);
169                 if (bytes_read < m_libdispatch_offsets.dqo_label_size)
170                     dispatch_queue_name.erase (bytes_read);
171             }
172         }
173     }
174     return dispatch_queue_name;
175 }
176 
177 lldb::queue_id_t
178 SystemRuntimeMacOSX::GetQueueIDFromThreadQAddress (lldb::addr_t dispatch_qaddr)
179 {
180     queue_id_t queue_id = LLDB_INVALID_QUEUE_ID;
181 
182     if (dispatch_qaddr == LLDB_INVALID_ADDRESS || dispatch_qaddr == 0)
183         return queue_id;
184 
185     ReadLibdispatchOffsets ();
186     if (m_libdispatch_offsets.IsValid ())
187     {
188         // dispatch_qaddr is from a thread_info(THREAD_IDENTIFIER_INFO) call for a thread -
189         // deref it to get the address of the dispatch_queue_t structure for this thread's
190         // queue.
191         Error error;
192         uint64_t dispatch_queue_addr = m_process->ReadPointerFromMemory (dispatch_qaddr, error);
193         if (error.Success())
194         {
195             addr_t serialnum_address = dispatch_queue_addr + m_libdispatch_offsets.dqo_serialnum;
196             queue_id_t serialnum = m_process->ReadUnsignedIntegerFromMemory (serialnum_address, m_libdispatch_offsets.dqo_serialnum_size, LLDB_INVALID_QUEUE_ID, error);
197             if (error.Success())
198             {
199                 queue_id = serialnum;
200             }
201         }
202     }
203 
204     return queue_id;
205 }
206 
207 
208 void
209 SystemRuntimeMacOSX::ReadLibdispatchOffsetsAddress ()
210 {
211     if (m_dispatch_queue_offsets_addr != LLDB_INVALID_ADDRESS)
212         return;
213 
214     static ConstString g_dispatch_queue_offsets_symbol_name ("dispatch_queue_offsets");
215     const Symbol *dispatch_queue_offsets_symbol = NULL;
216 
217     // libdispatch symbols were in libSystem.B.dylib up through Mac OS X 10.6 ("Snow Leopard")
218     ModuleSpec libSystem_module_spec (FileSpec("libSystem.B.dylib", false));
219     ModuleSP module_sp(m_process->GetTarget().GetImages().FindFirstModule (libSystem_module_spec));
220     if (module_sp)
221         dispatch_queue_offsets_symbol = module_sp->FindFirstSymbolWithNameAndType (g_dispatch_queue_offsets_symbol_name, eSymbolTypeData);
222 
223     // libdispatch symbols are in their own dylib as of Mac OS X 10.7 ("Lion") and later
224     if (dispatch_queue_offsets_symbol == NULL)
225     {
226         ModuleSpec libdispatch_module_spec (FileSpec("libdispatch.dylib", false));
227         module_sp = m_process->GetTarget().GetImages().FindFirstModule (libdispatch_module_spec);
228         if (module_sp)
229             dispatch_queue_offsets_symbol = module_sp->FindFirstSymbolWithNameAndType (g_dispatch_queue_offsets_symbol_name, eSymbolTypeData);
230     }
231     if (dispatch_queue_offsets_symbol)
232         m_dispatch_queue_offsets_addr = dispatch_queue_offsets_symbol->GetAddress().GetLoadAddress(&m_process->GetTarget());
233 }
234 
235 void
236 SystemRuntimeMacOSX::ReadLibdispatchOffsets ()
237 {
238     if (m_libdispatch_offsets.IsValid())
239         return;
240 
241     ReadLibdispatchOffsetsAddress ();
242 
243     uint8_t memory_buffer[sizeof (struct LibdispatchOffsets)];
244     DataExtractor data (memory_buffer,
245                         sizeof(memory_buffer),
246                         m_process->GetByteOrder(),
247                         m_process->GetAddressByteSize());
248 
249     Error error;
250     if (m_process->ReadMemory (m_dispatch_queue_offsets_addr, memory_buffer, sizeof(memory_buffer), error) == sizeof(memory_buffer))
251     {
252         lldb::offset_t data_offset = 0;
253 
254         // The struct LibdispatchOffsets is a series of uint16_t's - extract them all
255         // in one big go.
256         data.GetU16 (&data_offset, &m_libdispatch_offsets.dqo_version, sizeof (struct LibdispatchOffsets) / sizeof (uint16_t));
257     }
258 }
259 
260 
261 ThreadSP
262 SystemRuntimeMacOSX::GetExtendedBacktraceThread (ThreadSP real_thread, ConstString type)
263 {
264     ThreadSP originating_thread_sp;
265     if (BacktraceRecordingHeadersInitialized() && type == ConstString ("libdispatch"))
266     {
267         Error error;
268 
269         // real_thread is either an actual, live thread (in which case we need to call into
270         // libBacktraceRecording to find its originator) or it is an extended backtrace itself,
271         // in which case we get the token from it and call into libBacktraceRecording to find
272         // the originator of that token.
273 
274         if (real_thread->GetExtendedBacktraceToken() != LLDB_INVALID_ADDRESS)
275         {
276             originating_thread_sp = GetExtendedBacktraceFromItemRef (real_thread->GetExtendedBacktraceToken());
277         }
278         else
279         {
280             ThreadSP cur_thread_sp (m_process->GetThreadList().GetSelectedThread());
281             AppleGetThreadItemInfoHandler::GetThreadItemInfoReturnInfo ret = m_get_thread_item_info_handler.GetThreadItemInfo (*cur_thread_sp.get(), real_thread->GetID(), m_page_to_free, m_page_to_free_size, error);
282             m_page_to_free = LLDB_INVALID_ADDRESS;
283             m_page_to_free_size = 0;
284             if (ret.item_buffer_ptr != 0 &&  ret.item_buffer_ptr != LLDB_INVALID_ADDRESS && ret.item_buffer_size > 0)
285             {
286                 DataBufferHeap data (ret.item_buffer_size, 0);
287                 if (m_process->ReadMemory (ret.item_buffer_ptr, data.GetBytes(), ret.item_buffer_size, error) && error.Success())
288                 {
289                     DataExtractor extractor (data.GetBytes(), data.GetByteSize(), m_process->GetByteOrder(), m_process->GetAddressByteSize());
290                     ItemInfo item = ExtractItemInfoFromBuffer (extractor);
291                     bool stop_id_is_valid = true;
292                     if (item.stop_id == 0)
293                         stop_id_is_valid = false;
294                     originating_thread_sp.reset (new HistoryThread (*m_process,
295                                                                     item.enqueuing_thread_id,
296                                                                     item.enqueuing_callstack,
297                                                                     item.stop_id,
298                                                                     stop_id_is_valid));
299                     originating_thread_sp->SetExtendedBacktraceToken (item.item_that_enqueued_this);
300                     originating_thread_sp->SetQueueName (item.enqueuing_queue_label.c_str());
301                     originating_thread_sp->SetQueueID (item.enqueuing_queue_serialnum);
302 //                    originating_thread_sp->SetThreadName (item.enqueuing_thread_label.c_str());
303                 }
304                 m_page_to_free = ret.item_buffer_ptr;
305                 m_page_to_free_size = ret.item_buffer_size;
306             }
307         }
308     }
309     return originating_thread_sp;
310 }
311 
312 ThreadSP
313 SystemRuntimeMacOSX::GetExtendedBacktraceFromItemRef (lldb::addr_t item_ref)
314 {
315     ThreadSP return_thread_sp;
316 
317     AppleGetItemInfoHandler::GetItemInfoReturnInfo ret;
318     ThreadSP cur_thread_sp (m_process->GetThreadList().GetSelectedThread());
319     Error error;
320     ret = m_get_item_info_handler.GetItemInfo (*cur_thread_sp.get(), item_ref, m_page_to_free, m_page_to_free_size, error);
321     m_page_to_free = LLDB_INVALID_ADDRESS;
322     m_page_to_free_size = 0;
323     if (ret.item_buffer_ptr != 0 &&  ret.item_buffer_ptr != LLDB_INVALID_ADDRESS && ret.item_buffer_size > 0)
324     {
325         DataBufferHeap data (ret.item_buffer_size, 0);
326         if (m_process->ReadMemory (ret.item_buffer_ptr, data.GetBytes(), ret.item_buffer_size, error) && error.Success())
327         {
328             DataExtractor extractor (data.GetBytes(), data.GetByteSize(), m_process->GetByteOrder(), m_process->GetAddressByteSize());
329             ItemInfo item = ExtractItemInfoFromBuffer (extractor);
330             bool stop_id_is_valid = true;
331             if (item.stop_id == 0)
332                 stop_id_is_valid = false;
333             return_thread_sp.reset (new HistoryThread (*m_process,
334                                                             item.enqueuing_thread_id,
335                                                             item.enqueuing_callstack,
336                                                             item.stop_id,
337                                                             stop_id_is_valid));
338             return_thread_sp->SetExtendedBacktraceToken (item.item_that_enqueued_this);
339             return_thread_sp->SetQueueName (item.enqueuing_queue_label.c_str());
340             return_thread_sp->SetQueueID (item.enqueuing_queue_serialnum);
341 //            return_thread_sp->SetThreadName (item.enqueuing_thread_label.c_str());
342 
343             m_page_to_free = ret.item_buffer_ptr;
344             m_page_to_free_size = ret.item_buffer_size;
345         }
346     }
347     return return_thread_sp;
348 }
349 
350 ThreadSP
351 SystemRuntimeMacOSX::GetExtendedBacktraceForQueueItem (QueueItemSP queue_item_sp, ConstString type)
352 {
353     ThreadSP extended_thread_sp;
354     if (type != ConstString("libdispatch"))
355         return extended_thread_sp;
356 
357     bool stop_id_is_valid = true;
358     if (queue_item_sp->GetStopID() == 0)
359         stop_id_is_valid = false;
360 
361     extended_thread_sp.reset (new HistoryThread (*m_process,
362                                                  queue_item_sp->GetEnqueueingThreadID(),
363                                                  queue_item_sp->GetEnqueueingBacktrace(),
364                                                  queue_item_sp->GetStopID(),
365                                                  stop_id_is_valid));
366     extended_thread_sp->SetExtendedBacktraceToken (queue_item_sp->GetItemThatEnqueuedThis());
367     extended_thread_sp->SetQueueName (queue_item_sp->GetQueueLabel().c_str());
368     extended_thread_sp->SetQueueID (queue_item_sp->GetEnqueueingQueueID());
369 //    extended_thread_sp->SetThreadName (queue_item_sp->GetThreadLabel().c_str());
370 
371     return extended_thread_sp;
372 }
373 
374 /* Returns true if we were able to get the version / offset information
375  * out of libBacktraceRecording.  false means we were unable to retrieve
376  * this; the queue_info_version field will be 0.
377  */
378 
379 bool
380 SystemRuntimeMacOSX::BacktraceRecordingHeadersInitialized ()
381 {
382     if (m_lib_backtrace_recording_info.queue_info_version != 0)
383         return true;
384 
385     addr_t queue_info_version_address = LLDB_INVALID_ADDRESS;
386     addr_t queue_info_data_offset_address = LLDB_INVALID_ADDRESS;
387     addr_t item_info_version_address = LLDB_INVALID_ADDRESS;
388     addr_t item_info_data_offset_address = LLDB_INVALID_ADDRESS;
389     Target &target = m_process->GetTarget();
390 
391 
392     static ConstString introspection_dispatch_queue_info_version ("__introspection_dispatch_queue_info_version");
393     SymbolContextList sc_list;
394     if (m_process->GetTarget().GetImages().FindSymbolsWithNameAndType (introspection_dispatch_queue_info_version, eSymbolTypeData, sc_list) > 0)
395     {
396         SymbolContext sc;
397         sc_list.GetContextAtIndex (0, sc);
398         AddressRange addr_range;
399         sc.GetAddressRange (eSymbolContextSymbol, 0, false, addr_range);
400         queue_info_version_address = addr_range.GetBaseAddress().GetLoadAddress(&target);
401     }
402     sc_list.Clear();
403 
404     static ConstString introspection_dispatch_queue_info_data_offset ("__introspection_dispatch_queue_info_data_offset");
405     if (m_process->GetTarget().GetImages().FindSymbolsWithNameAndType (introspection_dispatch_queue_info_data_offset, eSymbolTypeData, sc_list) > 0)
406     {
407         SymbolContext sc;
408         sc_list.GetContextAtIndex (0, sc);
409         AddressRange addr_range;
410         sc.GetAddressRange (eSymbolContextSymbol, 0, false, addr_range);
411         queue_info_data_offset_address = addr_range.GetBaseAddress().GetLoadAddress(&target);
412     }
413     sc_list.Clear();
414 
415     static ConstString introspection_dispatch_item_info_version ("__introspection_dispatch_item_info_version");
416     if (m_process->GetTarget().GetImages().FindSymbolsWithNameAndType (introspection_dispatch_item_info_version, eSymbolTypeData, sc_list) > 0)
417     {
418         SymbolContext sc;
419         sc_list.GetContextAtIndex (0, sc);
420         AddressRange addr_range;
421         sc.GetAddressRange (eSymbolContextSymbol, 0, false, addr_range);
422         item_info_version_address = addr_range.GetBaseAddress().GetLoadAddress(&target);
423     }
424     sc_list.Clear();
425 
426     static ConstString introspection_dispatch_item_info_data_offset ("__introspection_dispatch_item_info_data_offset");
427     if (m_process->GetTarget().GetImages().FindSymbolsWithNameAndType (introspection_dispatch_item_info_data_offset, eSymbolTypeData, sc_list) > 0)
428     {
429         SymbolContext sc;
430         sc_list.GetContextAtIndex (0, sc);
431         AddressRange addr_range;
432         sc.GetAddressRange (eSymbolContextSymbol, 0, false, addr_range);
433         item_info_data_offset_address = addr_range.GetBaseAddress().GetLoadAddress(&target);
434     }
435 
436     if (queue_info_version_address != LLDB_INVALID_ADDRESS
437         && queue_info_data_offset_address != LLDB_INVALID_ADDRESS
438         && item_info_version_address != LLDB_INVALID_ADDRESS
439         && item_info_data_offset_address != LLDB_INVALID_ADDRESS)
440     {
441         Error error;
442         m_lib_backtrace_recording_info.queue_info_version = m_process->ReadUnsignedIntegerFromMemory (queue_info_version_address, 2, 0, error);
443         if (error.Success())
444         {
445             m_lib_backtrace_recording_info.queue_info_data_offset = m_process->ReadUnsignedIntegerFromMemory (queue_info_data_offset_address, 2, 0, error);
446             if (error.Success())
447             {
448                 m_lib_backtrace_recording_info.item_info_version = m_process->ReadUnsignedIntegerFromMemory (item_info_version_address, 2, 0, error);
449                 if (error.Success())
450                 {
451                     m_lib_backtrace_recording_info.item_info_data_offset = m_process->ReadUnsignedIntegerFromMemory (item_info_data_offset_address, 2, 0, error);
452                     if (!error.Success())
453                     {
454                         m_lib_backtrace_recording_info.queue_info_version = 0;
455                     }
456                 }
457                 else
458                 {
459                     m_lib_backtrace_recording_info.queue_info_version = 0;
460                 }
461             }
462             else
463             {
464                 m_lib_backtrace_recording_info.queue_info_version = 0;
465             }
466         }
467     }
468 
469     return m_lib_backtrace_recording_info.queue_info_version != 0;
470 }
471 
472 const std::vector<ConstString> &
473 SystemRuntimeMacOSX::GetExtendedBacktraceTypes ()
474 {
475     if (m_types.size () == 0)
476     {
477         m_types.push_back(ConstString("libdispatch"));
478         // We could have pthread as another type in the future if we have a way of
479         // gathering that information & it's useful to distinguish between them.
480     }
481     return m_types;
482 }
483 
484 void
485 SystemRuntimeMacOSX::PopulateQueueList (lldb_private::QueueList &queue_list)
486 {
487     if (!BacktraceRecordingHeadersInitialized())
488     {
489         // We don't have libBacktraceRecording -- build the list of queues by looking at
490         // all extant threads, and the queues that they currently belong to.
491 
492         for (ThreadSP thread_sp : m_process->Threads())
493         {
494             if (thread_sp->GetQueueID() != LLDB_INVALID_QUEUE_ID)
495             {
496                 if (queue_list.FindQueueByID (thread_sp->GetQueueID()).get() == NULL)
497                 {
498                     QueueSP queue_sp (new Queue(m_process->shared_from_this(), thread_sp->GetQueueID(), thread_sp->GetQueueName()));
499                     queue_list.AddQueue (queue_sp);
500                 }
501             }
502         }
503     }
504     else
505     {
506         AppleGetQueuesHandler::GetQueuesReturnInfo queue_info_pointer;
507         ThreadSP cur_thread_sp (m_process->GetThreadList().GetSelectedThread());
508         if (cur_thread_sp)
509         {
510             Error error;
511             queue_info_pointer = m_get_queues_handler.GetCurrentQueues (*cur_thread_sp.get(), m_page_to_free, m_page_to_free_size, error);
512             m_page_to_free = LLDB_INVALID_ADDRESS;
513             m_page_to_free_size = 0;
514             if (error.Success())
515             {
516 
517                 if (queue_info_pointer.count > 0
518                     && queue_info_pointer.queues_buffer_size > 0
519                     && queue_info_pointer.queues_buffer_ptr != 0
520                     && queue_info_pointer.queues_buffer_ptr != LLDB_INVALID_ADDRESS)
521                 {
522                     PopulateQueuesUsingLibBTR (queue_info_pointer.queues_buffer_ptr, queue_info_pointer.queues_buffer_size, queue_info_pointer.count, queue_list);
523                 }
524             }
525         }
526     }
527 }
528 
529 void
530 SystemRuntimeMacOSX::PopulatePendingItemsForQueue (Queue *queue)
531 {
532     if (BacktraceRecordingHeadersInitialized())
533     {
534         std::vector<addr_t> pending_item_refs = GetPendingItemRefsForQueue (queue->GetLibdispatchQueueAddress());
535         for (addr_t pending_item : pending_item_refs)
536         {
537             AppleGetItemInfoHandler::GetItemInfoReturnInfo ret;
538             ThreadSP cur_thread_sp (m_process->GetThreadList().GetSelectedThread());
539             Error error;
540             ret = m_get_item_info_handler.GetItemInfo (*cur_thread_sp.get(), pending_item, m_page_to_free, m_page_to_free_size, error);
541             m_page_to_free = LLDB_INVALID_ADDRESS;
542             m_page_to_free_size = 0;
543             if (ret.item_buffer_ptr != 0 &&  ret.item_buffer_ptr != LLDB_INVALID_ADDRESS && ret.item_buffer_size > 0)
544             {
545                 DataBufferHeap data (ret.item_buffer_size, 0);
546                 if (m_process->ReadMemory (ret.item_buffer_ptr, data.GetBytes(), ret.item_buffer_size, error) && error.Success())
547                 {
548                     DataExtractor extractor (data.GetBytes(), data.GetByteSize(), m_process->GetByteOrder(), m_process->GetAddressByteSize());
549                     ItemInfo item = ExtractItemInfoFromBuffer (extractor);
550                     QueueItemSP queue_item_sp (new QueueItem (queue->shared_from_this()));
551                     queue_item_sp->SetItemThatEnqueuedThis (item.item_that_enqueued_this);
552 
553                     Address addr;
554                     if (!m_process->GetTarget().ResolveLoadAddress (item.function_or_block, addr, item.stop_id))
555                     {
556                         m_process->GetTarget().ResolveLoadAddress (item.function_or_block, addr);
557                     }
558                     queue_item_sp->SetAddress (addr);
559                     queue_item_sp->SetEnqueueingThreadID (item.enqueuing_thread_id);
560                     queue_item_sp->SetTargetQueueID (item.enqueuing_thread_id);
561                     queue_item_sp->SetStopID (item.stop_id);
562                     queue_item_sp->SetEnqueueingBacktrace (item.enqueuing_callstack);
563                     queue_item_sp->SetThreadLabel (item.enqueuing_thread_label);
564                     queue_item_sp->SetQueueLabel (item.enqueuing_queue_label);
565                     queue_item_sp->SetTargetQueueLabel (item.target_queue_label);
566 
567                     queue->PushPendingQueueItem (queue_item_sp);
568                 }
569             }
570         }
571     }
572 }
573 
574 // Returns an array of introspection_dispatch_item_info_ref's for the pending items on
575 // a queue.  The information about each of these pending items then needs to be fetched
576 // individually by passing the ref to libBacktraceRecording.
577 
578 std::vector<lldb::addr_t>
579 SystemRuntimeMacOSX::GetPendingItemRefsForQueue (lldb::addr_t queue)
580 {
581     std::vector<addr_t> pending_item_refs;
582     AppleGetPendingItemsHandler::GetPendingItemsReturnInfo pending_items_pointer;
583     ThreadSP cur_thread_sp (m_process->GetThreadList().GetSelectedThread());
584     if (cur_thread_sp)
585     {
586         Error error;
587         pending_items_pointer = m_get_pending_items_handler.GetPendingItems (*cur_thread_sp.get(), queue, m_page_to_free, m_page_to_free_size, error);
588         m_page_to_free = LLDB_INVALID_ADDRESS;
589         m_page_to_free_size = 0;
590         if (error.Success())
591         {
592             if (pending_items_pointer.count > 0
593                 && pending_items_pointer.items_buffer_size > 0
594                 && pending_items_pointer.items_buffer_ptr != 0
595                 && pending_items_pointer.items_buffer_ptr != LLDB_INVALID_ADDRESS)
596             {
597                 DataBufferHeap data (pending_items_pointer.items_buffer_size, 0);
598                 if (m_process->ReadMemory (pending_items_pointer.items_buffer_ptr, data.GetBytes(), pending_items_pointer.items_buffer_size, error))
599                 {
600                     offset_t offset = 0;
601                     DataExtractor extractor (data.GetBytes(), data.GetByteSize(), m_process->GetByteOrder(), m_process->GetAddressByteSize());
602                     int i = 0;
603                     while (offset < pending_items_pointer.items_buffer_size && i < pending_items_pointer.count)
604                     {
605                         pending_item_refs.push_back (extractor.GetPointer (&offset));
606                         i++;
607                     }
608                 }
609                 m_page_to_free = pending_items_pointer.items_buffer_ptr;
610                 m_page_to_free_size = pending_items_pointer.items_buffer_size;
611             }
612         }
613     }
614     return pending_item_refs;
615 }
616 
617 
618 void
619 SystemRuntimeMacOSX::PopulateQueuesUsingLibBTR (lldb::addr_t queues_buffer, uint64_t queues_buffer_size,
620                                                 uint64_t count, lldb_private::QueueList &queue_list)
621 {
622     Error error;
623     DataBufferHeap data (queues_buffer_size, 0);
624     if (m_process->ReadMemory (queues_buffer, data.GetBytes(), queues_buffer_size, error) == queues_buffer_size && error.Success())
625     {
626         // We've read the information out of inferior memory; free it on the next call we make
627         m_page_to_free = queues_buffer;
628         m_page_to_free_size = queues_buffer_size;
629 
630         DataExtractor extractor (data.GetBytes(), data.GetByteSize(), m_process->GetByteOrder(), m_process->GetAddressByteSize());
631         offset_t offset = 0;
632         uint64_t queues_read = 0;
633 
634         // The information about the queues is stored in this format (v1):
635         // typedef struct introspection_dispatch_queue_info_s {
636         //     uint32_t offset_to_next;
637         //     dispatch_queue_t queue;
638         //     uint64_t serialnum;     // queue's serialnum in the process, as provided by libdispatch
639         //     uint32_t running_work_items_count;
640         //     uint32_t pending_work_items_count;
641         //
642         //     char data[];     // Starting here, we have variable-length data:
643         //     // char queue_label[];
644         // } introspection_dispatch_queue_info_s;
645 
646         while (queues_read < count && offset < queues_buffer_size)
647         {
648             offset_t    start_of_this_item = offset;
649 
650             uint32_t    offset_to_next = extractor.GetU32 (&offset);
651             /* on 64-bit architectures, the pointer will be 8-byte aligned so there's 4 bytes of
652              * padding between these fields.
653              */
654             if (m_process->GetAddressByteSize() == 8)
655                 offset += 4;
656             addr_t      queue = extractor.GetPointer (&offset);
657             uint64_t    serialnum = extractor.GetU64 (&offset);
658             uint32_t    running_work_items_count = extractor.GetU32 (&offset);
659             uint32_t    pending_work_items_count = extractor.GetU32 (&offset);
660 
661             // Read the first field of the variable length data
662             offset = start_of_this_item + m_lib_backtrace_recording_info.queue_info_data_offset;
663             const char *queue_label = extractor.GetCStr (&offset);
664             if (queue_label == NULL)
665                 queue_label = "";
666 
667             offset_t    start_of_next_item = start_of_this_item + offset_to_next;
668             offset = start_of_next_item;
669 
670             QueueSP queue_sp (new Queue (m_process->shared_from_this(), serialnum, queue_label));
671             queue_sp->SetNumRunningWorkItems (running_work_items_count);
672             queue_sp->SetNumPendingWorkItems (pending_work_items_count);
673             queue_sp->SetLibdispatchQueueAddress (queue);
674             queue_list.AddQueue (queue_sp);
675             queues_read++;
676         }
677     }
678 }
679 
680 SystemRuntimeMacOSX::ItemInfo
681 SystemRuntimeMacOSX::ExtractItemInfoFromBuffer (lldb_private::DataExtractor &extractor)
682 {
683     ItemInfo item;
684 
685     offset_t offset = 0;
686 
687     item.item_that_enqueued_this = extractor.GetPointer (&offset);
688     item.function_or_block = extractor.GetPointer (&offset);
689     item.enqueuing_thread_id = extractor.GetU64 (&offset);
690     item.enqueuing_queue_serialnum = extractor.GetU64 (&offset);
691     item.target_queue_serialnum = extractor.GetU64 (&offset);
692     item.enqueuing_callstack_frame_count = extractor.GetU32 (&offset);
693     item.stop_id = extractor.GetU32 (&offset);
694 
695     offset = m_lib_backtrace_recording_info.item_info_data_offset;
696 
697     for (uint32_t i = 0; i < item.enqueuing_callstack_frame_count; i++)
698     {
699         item.enqueuing_callstack.push_back (extractor.GetPointer (&offset));
700     }
701     item.enqueuing_thread_label = extractor.GetCStr (&offset);
702     item.enqueuing_queue_label = extractor.GetCStr (&offset);
703     item.target_queue_label = extractor.GetCStr (&offset);
704 
705     return item;
706 }
707 
708 void
709 SystemRuntimeMacOSX::Initialize()
710 {
711     PluginManager::RegisterPlugin (GetPluginNameStatic(),
712                                    GetPluginDescriptionStatic(),
713                                    CreateInstance);
714 }
715 
716 void
717 SystemRuntimeMacOSX::Terminate()
718 {
719     PluginManager::UnregisterPlugin (CreateInstance);
720 }
721 
722 
723 lldb_private::ConstString
724 SystemRuntimeMacOSX::GetPluginNameStatic()
725 {
726     static ConstString g_name("systemruntime-macosx");
727     return g_name;
728 }
729 
730 const char *
731 SystemRuntimeMacOSX::GetPluginDescriptionStatic()
732 {
733     return "System runtime plugin for Mac OS X native libraries.";
734 }
735 
736 
737 //------------------------------------------------------------------
738 // PluginInterface protocol
739 //------------------------------------------------------------------
740 lldb_private::ConstString
741 SystemRuntimeMacOSX::GetPluginName()
742 {
743     return GetPluginNameStatic();
744 }
745 
746 uint32_t
747 SystemRuntimeMacOSX::GetPluginVersion()
748 {
749     return 1;
750 }
751