1 //===-- LibCxx.cpp ----------------------------------------------*- C++ -*-===//
2 //
3 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
4 // See https://llvm.org/LICENSE.txt for license information.
5 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
6 //
7 //===----------------------------------------------------------------------===//
8 
9 #include "LibCxx.h"
10 
11 #include "llvm/ADT/ScopeExit.h"
12 #include "lldb/Core/Debugger.h"
13 #include "lldb/Core/FormatEntity.h"
14 #include "lldb/Core/ValueObject.h"
15 #include "lldb/Core/ValueObjectConstResult.h"
16 #include "lldb/DataFormatters/FormattersHelpers.h"
17 #include "lldb/DataFormatters/StringPrinter.h"
18 #include "lldb/DataFormatters/TypeSummary.h"
19 #include "lldb/DataFormatters/VectorIterator.h"
20 #include "lldb/Symbol/ClangASTContext.h"
21 #include "lldb/Target/CPPLanguageRuntime.h"
22 #include "lldb/Target/ProcessStructReader.h"
23 #include "lldb/Target/SectionLoadList.h"
24 #include "lldb/Target/Target.h"
25 #include "lldb/Utility/DataBufferHeap.h"
26 #include "lldb/Utility/Endian.h"
27 #include "lldb/Utility/Status.h"
28 #include "lldb/Utility/Stream.h"
29 
30 using namespace lldb;
31 using namespace lldb_private;
32 using namespace lldb_private::formatters;
33 
34 bool lldb_private::formatters::LibcxxOptionalSummaryProvider(
35     ValueObject &valobj, Stream &stream, const TypeSummaryOptions &options) {
36   ValueObjectSP valobj_sp(valobj.GetNonSyntheticValue());
37   if (!valobj_sp)
38     return false;
39 
40   // An optional either contains a value or not, the member __engaged_ is
41   // a bool flag, it is true if the optional has a value and false otherwise.
42   ValueObjectSP engaged_sp(
43       valobj_sp->GetChildMemberWithName(ConstString("__engaged_"), true));
44 
45   if (!engaged_sp)
46     return false;
47 
48   llvm::StringRef engaged_as_cstring(
49       engaged_sp->GetValueAsUnsigned(0) == 1 ? "true" : "false");
50 
51   stream.Printf(" Has Value=%s ", engaged_as_cstring.data());
52 
53   return true;
54 }
55 
56 bool lldb_private::formatters::LibcxxFunctionSummaryProvider(
57     ValueObject &valobj, Stream &stream, const TypeSummaryOptions &options) {
58 
59   ValueObjectSP valobj_sp(valobj.GetNonSyntheticValue());
60 
61   if (!valobj_sp)
62     return false;
63 
64   ExecutionContext exe_ctx(valobj_sp->GetExecutionContextRef());
65   Process *process = exe_ctx.GetProcessPtr();
66 
67   if (process == nullptr)
68     return false;
69 
70   CPPLanguageRuntime *cpp_runtime = process->GetCPPLanguageRuntime();
71 
72   if (!cpp_runtime)
73     return false;
74 
75   CPPLanguageRuntime::LibCppStdFunctionCallableInfo callable_info =
76       cpp_runtime->FindLibCppStdFunctionCallableInfo(valobj_sp);
77 
78   switch (callable_info.callable_case) {
79   case CPPLanguageRuntime::LibCppStdFunctionCallableCase::Invalid:
80     stream.Printf(" __f_ = %" PRIu64, callable_info.member__f_pointer_value);
81     return false;
82     break;
83   case CPPLanguageRuntime::LibCppStdFunctionCallableCase::Lambda:
84     stream.Printf(
85         " Lambda in File %s at Line %u",
86         callable_info.callable_line_entry.file.GetFilename().GetCString(),
87         callable_info.callable_line_entry.line);
88     break;
89   case CPPLanguageRuntime::LibCppStdFunctionCallableCase::CallableObject:
90     stream.Printf(
91         " Function in File %s at Line %u",
92         callable_info.callable_line_entry.file.GetFilename().GetCString(),
93         callable_info.callable_line_entry.line);
94     break;
95   case CPPLanguageRuntime::LibCppStdFunctionCallableCase::FreeOrMemberFunction:
96     stream.Printf(" Function = %s ",
97                   callable_info.callable_symbol.GetName().GetCString());
98     break;
99   }
100 
101   return true;
102 }
103 
104 bool lldb_private::formatters::LibcxxSmartPointerSummaryProvider(
105     ValueObject &valobj, Stream &stream, const TypeSummaryOptions &options) {
106   ValueObjectSP valobj_sp(valobj.GetNonSyntheticValue());
107   if (!valobj_sp)
108     return false;
109   ValueObjectSP ptr_sp(
110       valobj_sp->GetChildMemberWithName(ConstString("__ptr_"), true));
111   ValueObjectSP count_sp(valobj_sp->GetChildAtNamePath(
112       {ConstString("__cntrl_"), ConstString("__shared_owners_")}));
113   ValueObjectSP weakcount_sp(valobj_sp->GetChildAtNamePath(
114       {ConstString("__cntrl_"), ConstString("__shared_weak_owners_")}));
115 
116   if (!ptr_sp)
117     return false;
118 
119   if (ptr_sp->GetValueAsUnsigned(0) == 0) {
120     stream.Printf("nullptr");
121     return true;
122   } else {
123     bool print_pointee = false;
124     Status error;
125     ValueObjectSP pointee_sp = ptr_sp->Dereference(error);
126     if (pointee_sp && error.Success()) {
127       if (pointee_sp->DumpPrintableRepresentation(
128               stream, ValueObject::eValueObjectRepresentationStyleSummary,
129               lldb::eFormatInvalid,
130               ValueObject::PrintableRepresentationSpecialCases::eDisable,
131               false))
132         print_pointee = true;
133     }
134     if (!print_pointee)
135       stream.Printf("ptr = 0x%" PRIx64, ptr_sp->GetValueAsUnsigned(0));
136   }
137 
138   if (count_sp)
139     stream.Printf(" strong=%" PRIu64, 1 + count_sp->GetValueAsUnsigned(0));
140 
141   if (weakcount_sp)
142     stream.Printf(" weak=%" PRIu64, 1 + weakcount_sp->GetValueAsUnsigned(0));
143 
144   return true;
145 }
146 
147 /*
148  (lldb) fr var ibeg --raw --ptr-depth 1
149  (std::__1::__map_iterator<std::__1::__tree_iterator<std::__1::pair<int,
150  std::__1::basic_string<char, std::__1::char_traits<char>,
151  std::__1::allocator<char> > >, std::__1::__tree_node<std::__1::pair<int,
152  std::__1::basic_string<char, std::__1::char_traits<char>,
153  std::__1::allocator<char> > >, void *> *, long> >) ibeg = {
154  __i_ = {
155  __ptr_ = 0x0000000100103870 {
156  std::__1::__tree_node_base<void *> = {
157  std::__1::__tree_end_node<std::__1::__tree_node_base<void *> *> = {
158  __left_ = 0x0000000000000000
159  }
160  __right_ = 0x0000000000000000
161  __parent_ = 0x00000001001038b0
162  __is_black_ = true
163  }
164  __value_ = {
165  first = 0
166  second = { std::string }
167  */
168 
169 lldb_private::formatters::LibCxxMapIteratorSyntheticFrontEnd::
170     LibCxxMapIteratorSyntheticFrontEnd(lldb::ValueObjectSP valobj_sp)
171     : SyntheticChildrenFrontEnd(*valobj_sp), m_pair_ptr(), m_pair_sp() {
172   if (valobj_sp)
173     Update();
174 }
175 
176 bool lldb_private::formatters::LibCxxMapIteratorSyntheticFrontEnd::Update() {
177   m_pair_sp.reset();
178   m_pair_ptr = nullptr;
179 
180   ValueObjectSP valobj_sp = m_backend.GetSP();
181   if (!valobj_sp)
182     return false;
183 
184   TargetSP target_sp(valobj_sp->GetTargetSP());
185 
186   if (!target_sp)
187     return false;
188 
189   if (!valobj_sp)
190     return false;
191 
192   static ConstString g___i_("__i_");
193 
194   // this must be a ValueObject* because it is a child of the ValueObject we
195   // are producing children for it if were a ValueObjectSP, we would end up
196   // with a loop (iterator -> synthetic -> child -> parent == iterator) and
197   // that would in turn leak memory by never allowing the ValueObjects to die
198   // and free their memory
199   m_pair_ptr = valobj_sp
200                    ->GetValueForExpressionPath(
201                        ".__i_.__ptr_->__value_", nullptr, nullptr,
202                        ValueObject::GetValueForExpressionPathOptions()
203                            .DontCheckDotVsArrowSyntax()
204                            .SetSyntheticChildrenTraversal(
205                                ValueObject::GetValueForExpressionPathOptions::
206                                    SyntheticChildrenTraversal::None),
207                        nullptr)
208                    .get();
209 
210   if (!m_pair_ptr) {
211     m_pair_ptr = valobj_sp
212                      ->GetValueForExpressionPath(
213                          ".__i_.__ptr_", nullptr, nullptr,
214                          ValueObject::GetValueForExpressionPathOptions()
215                              .DontCheckDotVsArrowSyntax()
216                              .SetSyntheticChildrenTraversal(
217                                  ValueObject::GetValueForExpressionPathOptions::
218                                      SyntheticChildrenTraversal::None),
219                          nullptr)
220                      .get();
221     if (m_pair_ptr) {
222       auto __i_(valobj_sp->GetChildMemberWithName(g___i_, true));
223       if (!__i_) {
224         m_pair_ptr = nullptr;
225         return false;
226       }
227       CompilerType pair_type(
228           __i_->GetCompilerType().GetTypeTemplateArgument(0));
229       std::string name;
230       uint64_t bit_offset_ptr;
231       uint32_t bitfield_bit_size_ptr;
232       bool is_bitfield_ptr;
233       pair_type = pair_type.GetFieldAtIndex(
234           0, name, &bit_offset_ptr, &bitfield_bit_size_ptr, &is_bitfield_ptr);
235       if (!pair_type) {
236         m_pair_ptr = nullptr;
237         return false;
238       }
239 
240       auto addr(m_pair_ptr->GetValueAsUnsigned(LLDB_INVALID_ADDRESS));
241       m_pair_ptr = nullptr;
242       if (addr && addr != LLDB_INVALID_ADDRESS) {
243         ClangASTContext *ast_ctx =
244             llvm::dyn_cast_or_null<ClangASTContext>(pair_type.GetTypeSystem());
245         if (!ast_ctx)
246           return false;
247         CompilerType tree_node_type = ast_ctx->CreateStructForIdentifier(
248             ConstString(),
249             {{"ptr0",
250               ast_ctx->GetBasicType(lldb::eBasicTypeVoid).GetPointerType()},
251              {"ptr1",
252               ast_ctx->GetBasicType(lldb::eBasicTypeVoid).GetPointerType()},
253              {"ptr2",
254               ast_ctx->GetBasicType(lldb::eBasicTypeVoid).GetPointerType()},
255              {"cw", ast_ctx->GetBasicType(lldb::eBasicTypeBool)},
256              {"payload", pair_type}});
257         llvm::Optional<uint64_t> size = tree_node_type.GetByteSize(nullptr);
258         if (!size)
259           return false;
260         DataBufferSP buffer_sp(new DataBufferHeap(*size, 0));
261         ProcessSP process_sp(target_sp->GetProcessSP());
262         Status error;
263         process_sp->ReadMemory(addr, buffer_sp->GetBytes(),
264                                buffer_sp->GetByteSize(), error);
265         if (error.Fail())
266           return false;
267         DataExtractor extractor(buffer_sp, process_sp->GetByteOrder(),
268                                 process_sp->GetAddressByteSize());
269         auto pair_sp = CreateValueObjectFromData(
270             "pair", extractor, valobj_sp->GetExecutionContextRef(),
271             tree_node_type);
272         if (pair_sp)
273           m_pair_sp = pair_sp->GetChildAtIndex(4, true);
274       }
275     }
276   }
277 
278   return false;
279 }
280 
281 size_t lldb_private::formatters::LibCxxMapIteratorSyntheticFrontEnd::
282     CalculateNumChildren() {
283   return 2;
284 }
285 
286 lldb::ValueObjectSP
287 lldb_private::formatters::LibCxxMapIteratorSyntheticFrontEnd::GetChildAtIndex(
288     size_t idx) {
289   if (m_pair_ptr)
290     return m_pair_ptr->GetChildAtIndex(idx, true);
291   if (m_pair_sp)
292     return m_pair_sp->GetChildAtIndex(idx, true);
293   return lldb::ValueObjectSP();
294 }
295 
296 bool lldb_private::formatters::LibCxxMapIteratorSyntheticFrontEnd::
297     MightHaveChildren() {
298   return true;
299 }
300 
301 size_t lldb_private::formatters::LibCxxMapIteratorSyntheticFrontEnd::
302     GetIndexOfChildWithName(ConstString name) {
303   if (name == ConstString("first"))
304     return 0;
305   if (name == ConstString("second"))
306     return 1;
307   return UINT32_MAX;
308 }
309 
310 lldb_private::formatters::LibCxxMapIteratorSyntheticFrontEnd::
311     ~LibCxxMapIteratorSyntheticFrontEnd() {
312   // this will be deleted when its parent dies (since it's a child object)
313   // delete m_pair_ptr;
314 }
315 
316 SyntheticChildrenFrontEnd *
317 lldb_private::formatters::LibCxxMapIteratorSyntheticFrontEndCreator(
318     CXXSyntheticChildren *, lldb::ValueObjectSP valobj_sp) {
319   return (valobj_sp ? new LibCxxMapIteratorSyntheticFrontEnd(valobj_sp)
320                     : nullptr);
321 }
322 
323 /*
324  (lldb) fr var ibeg --raw --ptr-depth 1 -T
325  (std::__1::__wrap_iter<int *>) ibeg = {
326  (std::__1::__wrap_iter<int *>::iterator_type) __i = 0x00000001001037a0 {
327  (int) *__i = 1
328  }
329  }
330 */
331 
332 SyntheticChildrenFrontEnd *
333 lldb_private::formatters::LibCxxVectorIteratorSyntheticFrontEndCreator(
334     CXXSyntheticChildren *, lldb::ValueObjectSP valobj_sp) {
335   static ConstString g_item_name;
336   if (!g_item_name)
337     g_item_name.SetCString("__i");
338   return (valobj_sp
339               ? new VectorIteratorSyntheticFrontEnd(valobj_sp, g_item_name)
340               : nullptr);
341 }
342 
343 lldb_private::formatters::LibcxxSharedPtrSyntheticFrontEnd::
344     LibcxxSharedPtrSyntheticFrontEnd(lldb::ValueObjectSP valobj_sp)
345     : SyntheticChildrenFrontEnd(*valobj_sp), m_cntrl(nullptr), m_count_sp(),
346       m_weak_count_sp(), m_ptr_size(0), m_byte_order(lldb::eByteOrderInvalid) {
347   if (valobj_sp)
348     Update();
349 }
350 
351 size_t lldb_private::formatters::LibcxxSharedPtrSyntheticFrontEnd::
352     CalculateNumChildren() {
353   return (m_cntrl ? 1 : 0);
354 }
355 
356 lldb::ValueObjectSP
357 lldb_private::formatters::LibcxxSharedPtrSyntheticFrontEnd::GetChildAtIndex(
358     size_t idx) {
359   if (!m_cntrl)
360     return lldb::ValueObjectSP();
361 
362   ValueObjectSP valobj_sp = m_backend.GetSP();
363   if (!valobj_sp)
364     return lldb::ValueObjectSP();
365 
366   if (idx == 0)
367     return valobj_sp->GetChildMemberWithName(ConstString("__ptr_"), true);
368 
369   if (idx > 2)
370     return lldb::ValueObjectSP();
371 
372   if (idx == 1) {
373     if (!m_count_sp) {
374       ValueObjectSP shared_owners_sp(m_cntrl->GetChildMemberWithName(
375           ConstString("__shared_owners_"), true));
376       if (!shared_owners_sp)
377         return lldb::ValueObjectSP();
378       uint64_t count = 1 + shared_owners_sp->GetValueAsUnsigned(0);
379       DataExtractor data(&count, 8, m_byte_order, m_ptr_size);
380       m_count_sp = CreateValueObjectFromData(
381           "count", data, valobj_sp->GetExecutionContextRef(),
382           shared_owners_sp->GetCompilerType());
383     }
384     return m_count_sp;
385   } else /* if (idx == 2) */
386   {
387     if (!m_weak_count_sp) {
388       ValueObjectSP shared_weak_owners_sp(m_cntrl->GetChildMemberWithName(
389           ConstString("__shared_weak_owners_"), true));
390       if (!shared_weak_owners_sp)
391         return lldb::ValueObjectSP();
392       uint64_t count = 1 + shared_weak_owners_sp->GetValueAsUnsigned(0);
393       DataExtractor data(&count, 8, m_byte_order, m_ptr_size);
394       m_weak_count_sp = CreateValueObjectFromData(
395           "count", data, valobj_sp->GetExecutionContextRef(),
396           shared_weak_owners_sp->GetCompilerType());
397     }
398     return m_weak_count_sp;
399   }
400 }
401 
402 bool lldb_private::formatters::LibcxxSharedPtrSyntheticFrontEnd::Update() {
403   m_count_sp.reset();
404   m_weak_count_sp.reset();
405   m_cntrl = nullptr;
406 
407   ValueObjectSP valobj_sp = m_backend.GetSP();
408   if (!valobj_sp)
409     return false;
410 
411   TargetSP target_sp(valobj_sp->GetTargetSP());
412   if (!target_sp)
413     return false;
414 
415   m_byte_order = target_sp->GetArchitecture().GetByteOrder();
416   m_ptr_size = target_sp->GetArchitecture().GetAddressByteSize();
417 
418   lldb::ValueObjectSP cntrl_sp(
419       valobj_sp->GetChildMemberWithName(ConstString("__cntrl_"), true));
420 
421   m_cntrl = cntrl_sp.get(); // need to store the raw pointer to avoid a circular
422                             // dependency
423   return false;
424 }
425 
426 bool lldb_private::formatters::LibcxxSharedPtrSyntheticFrontEnd::
427     MightHaveChildren() {
428   return true;
429 }
430 
431 size_t lldb_private::formatters::LibcxxSharedPtrSyntheticFrontEnd::
432     GetIndexOfChildWithName(ConstString name) {
433   if (name == ConstString("__ptr_"))
434     return 0;
435   if (name == ConstString("count"))
436     return 1;
437   if (name == ConstString("weak_count"))
438     return 2;
439   return UINT32_MAX;
440 }
441 
442 lldb_private::formatters::LibcxxSharedPtrSyntheticFrontEnd::
443     ~LibcxxSharedPtrSyntheticFrontEnd() = default;
444 
445 SyntheticChildrenFrontEnd *
446 lldb_private::formatters::LibcxxSharedPtrSyntheticFrontEndCreator(
447     CXXSyntheticChildren *, lldb::ValueObjectSP valobj_sp) {
448   return (valobj_sp ? new LibcxxSharedPtrSyntheticFrontEnd(valobj_sp)
449                     : nullptr);
450 }
451 
452 bool lldb_private::formatters::LibcxxContainerSummaryProvider(
453     ValueObject &valobj, Stream &stream, const TypeSummaryOptions &options) {
454   if (valobj.IsPointerType()) {
455     uint64_t value = valobj.GetValueAsUnsigned(0);
456     if (!value)
457       return false;
458     stream.Printf("0x%016" PRIx64 " ", value);
459   }
460   return FormatEntity::FormatStringRef("size=${svar%#}", stream, nullptr,
461                                        nullptr, nullptr, &valobj, false, false);
462 }
463 
464 // the field layout in a libc++ string (cap, side, data or data, size, cap)
465 enum LibcxxStringLayoutMode {
466   eLibcxxStringLayoutModeCSD = 0,
467   eLibcxxStringLayoutModeDSC = 1,
468   eLibcxxStringLayoutModeInvalid = 0xffff
469 };
470 
471 // this function abstracts away the layout and mode details of a libc++ string
472 // and returns the address of the data and the size ready for callers to
473 // consume
474 static bool ExtractLibcxxStringInfo(ValueObject &valobj,
475                                     ValueObjectSP &location_sp,
476                                     uint64_t &size) {
477   ValueObjectSP D(valobj.GetChildAtIndexPath({0, 0, 0, 0}));
478   if (!D)
479     return false;
480 
481   ValueObjectSP layout_decider(
482     D->GetChildAtIndexPath(llvm::ArrayRef<size_t>({0, 0})));
483 
484   // this child should exist
485   if (!layout_decider)
486     return false;
487 
488   ConstString g_data_name("__data_");
489   ConstString g_size_name("__size_");
490   bool short_mode = false; // this means the string is in short-mode and the
491                            // data is stored inline
492   LibcxxStringLayoutMode layout = (layout_decider->GetName() == g_data_name)
493                                       ? eLibcxxStringLayoutModeDSC
494                                       : eLibcxxStringLayoutModeCSD;
495   uint64_t size_mode_value = 0;
496 
497   if (layout == eLibcxxStringLayoutModeDSC) {
498     ValueObjectSP size_mode(D->GetChildAtIndexPath({1, 1, 0}));
499     if (!size_mode)
500       return false;
501 
502     if (size_mode->GetName() != g_size_name) {
503       // we are hitting the padding structure, move along
504       size_mode = D->GetChildAtIndexPath({1, 1, 1});
505       if (!size_mode)
506         return false;
507     }
508 
509     size_mode_value = (size_mode->GetValueAsUnsigned(0));
510     short_mode = ((size_mode_value & 0x80) == 0);
511   } else {
512     ValueObjectSP size_mode(D->GetChildAtIndexPath({1, 0, 0}));
513     if (!size_mode)
514       return false;
515 
516     size_mode_value = (size_mode->GetValueAsUnsigned(0));
517     short_mode = ((size_mode_value & 1) == 0);
518   }
519 
520   if (short_mode) {
521     ValueObjectSP s(D->GetChildAtIndex(1, true));
522     if (!s)
523       return false;
524     location_sp = s->GetChildAtIndex(
525         (layout == eLibcxxStringLayoutModeDSC) ? 0 : 1, true);
526     size = (layout == eLibcxxStringLayoutModeDSC)
527                ? size_mode_value
528                : ((size_mode_value >> 1) % 256);
529     return (location_sp.get() != nullptr);
530   } else {
531     ValueObjectSP l(D->GetChildAtIndex(0, true));
532     if (!l)
533       return false;
534     // we can use the layout_decider object as the data pointer
535     location_sp = (layout == eLibcxxStringLayoutModeDSC)
536                       ? layout_decider
537                       : l->GetChildAtIndex(2, true);
538     ValueObjectSP size_vo(l->GetChildAtIndex(1, true));
539     if (!size_vo || !location_sp)
540       return false;
541     size = size_vo->GetValueAsUnsigned(0);
542     return true;
543   }
544 }
545 
546 bool lldb_private::formatters::LibcxxWStringSummaryProvider(
547     ValueObject &valobj, Stream &stream,
548     const TypeSummaryOptions &summary_options) {
549   uint64_t size = 0;
550   ValueObjectSP location_sp;
551   if (!ExtractLibcxxStringInfo(valobj, location_sp, size))
552     return false;
553   if (size == 0) {
554     stream.Printf("L\"\"");
555     return true;
556   }
557   if (!location_sp)
558     return false;
559 
560   DataExtractor extractor;
561 
562   StringPrinter::ReadBufferAndDumpToStreamOptions options(valobj);
563 
564   if (summary_options.GetCapping() == TypeSummaryCapping::eTypeSummaryCapped) {
565     const auto max_size = valobj.GetTargetSP()->GetMaximumSizeOfStringSummary();
566     if (size > max_size) {
567       size = max_size;
568       options.SetIsTruncated(true);
569     }
570   }
571   location_sp->GetPointeeData(extractor, 0, size);
572 
573   // std::wstring::size() is measured in 'characters', not bytes
574   auto wchar_t_size = valobj.GetTargetSP()
575                           ->GetScratchClangASTContext()
576                           ->GetBasicType(lldb::eBasicTypeWChar)
577                           .GetByteSize(nullptr);
578   if (!wchar_t_size)
579     return false;
580 
581   options.SetData(extractor);
582   options.SetStream(&stream);
583   options.SetPrefixToken("L");
584   options.SetQuote('"');
585   options.SetSourceSize(size);
586   options.SetBinaryZeroIsTerminator(false);
587 
588   switch (*wchar_t_size) {
589   case 1:
590     StringPrinter::ReadBufferAndDumpToStream<
591         lldb_private::formatters::StringPrinter::StringElementType::UTF8>(
592         options);
593     break;
594 
595   case 2:
596     lldb_private::formatters::StringPrinter::ReadBufferAndDumpToStream<
597         lldb_private::formatters::StringPrinter::StringElementType::UTF16>(
598         options);
599     break;
600 
601   case 4:
602     lldb_private::formatters::StringPrinter::ReadBufferAndDumpToStream<
603         lldb_private::formatters::StringPrinter::StringElementType::UTF32>(
604         options);
605     break;
606 
607   default:
608     stream.Printf("size for wchar_t is not valid");
609     return true;
610   }
611 
612   return true;
613 }
614 
615 template <StringPrinter::StringElementType element_type>
616 bool LibcxxStringSummaryProvider(ValueObject &valobj, Stream &stream,
617                                  const TypeSummaryOptions &summary_options,
618                                  std::string prefix_token = "") {
619   uint64_t size = 0;
620   ValueObjectSP location_sp;
621 
622   if (!ExtractLibcxxStringInfo(valobj, location_sp, size))
623     return false;
624 
625   if (size == 0) {
626     stream.Printf("\"\"");
627     return true;
628   }
629 
630   if (!location_sp)
631     return false;
632 
633   StringPrinter::ReadBufferAndDumpToStreamOptions options(valobj);
634 
635   DataExtractor extractor;
636   if (summary_options.GetCapping() == TypeSummaryCapping::eTypeSummaryCapped) {
637     const auto max_size = valobj.GetTargetSP()->GetMaximumSizeOfStringSummary();
638     if (size > max_size) {
639       size = max_size;
640       options.SetIsTruncated(true);
641     }
642   }
643   location_sp->GetPointeeData(extractor, 0, size);
644 
645   options.SetData(extractor);
646   options.SetStream(&stream);
647 
648   if (prefix_token.empty())
649     options.SetPrefixToken(nullptr);
650   else
651     options.SetPrefixToken(prefix_token);
652 
653   options.SetQuote('"');
654   options.SetSourceSize(size);
655   options.SetBinaryZeroIsTerminator(false);
656   StringPrinter::ReadBufferAndDumpToStream<element_type>(options);
657 
658   return true;
659 }
660 
661 bool lldb_private::formatters::LibcxxStringSummaryProviderASCII(
662     ValueObject &valobj, Stream &stream,
663     const TypeSummaryOptions &summary_options) {
664   return LibcxxStringSummaryProvider<StringPrinter::StringElementType::ASCII>(
665       valobj, stream, summary_options);
666 }
667 
668 bool lldb_private::formatters::LibcxxStringSummaryProviderUTF16(
669     ValueObject &valobj, Stream &stream,
670     const TypeSummaryOptions &summary_options) {
671   return LibcxxStringSummaryProvider<StringPrinter::StringElementType::UTF16>(
672       valobj, stream, summary_options, "u");
673 }
674 
675 bool lldb_private::formatters::LibcxxStringSummaryProviderUTF32(
676     ValueObject &valobj, Stream &stream,
677     const TypeSummaryOptions &summary_options) {
678   return LibcxxStringSummaryProvider<StringPrinter::StringElementType::UTF32>(
679       valobj, stream, summary_options, "U");
680 }
681