1 //===-- AppleObjCRuntime.cpp -------------------------------------*- C++
2 //-*-===//
3 //
4 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
5 // See https://llvm.org/LICENSE.txt for license information.
6 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
7 //
8 //===----------------------------------------------------------------------===//
9 
10 #include "AppleObjCRuntime.h"
11 #include "AppleObjCTrampolineHandler.h"
12 
13 #include "clang/AST/Type.h"
14 
15 #include "lldb/Breakpoint/BreakpointLocation.h"
16 #include "lldb/Core/Module.h"
17 #include "lldb/Core/ModuleList.h"
18 #include "lldb/Core/PluginManager.h"
19 #include "lldb/Core/Section.h"
20 #include "lldb/Core/ValueObject.h"
21 #include "lldb/Core/ValueObjectConstResult.h"
22 #include "lldb/DataFormatters/FormattersHelpers.h"
23 #include "lldb/Expression/DiagnosticManager.h"
24 #include "lldb/Expression/FunctionCaller.h"
25 #include "lldb/Symbol/ClangASTContext.h"
26 #include "lldb/Symbol/ObjectFile.h"
27 #include "lldb/Target/ExecutionContext.h"
28 #include "lldb/Target/Process.h"
29 #include "lldb/Target/RegisterContext.h"
30 #include "lldb/Target/StopInfo.h"
31 #include "lldb/Target/Target.h"
32 #include "lldb/Target/Thread.h"
33 #include "lldb/Utility/ConstString.h"
34 #include "lldb/Utility/Log.h"
35 #include "lldb/Utility/Scalar.h"
36 #include "lldb/Utility/Status.h"
37 #include "lldb/Utility/StreamString.h"
38 
39 #include "Plugins/Process/Utility/HistoryThread.h"
40 #include "Plugins/Language/ObjC/NSString.h"
41 #include "Plugins/LanguageRuntime/CPlusPlus/CPPLanguageRuntime.h"
42 
43 #include <vector>
44 
45 using namespace lldb;
46 using namespace lldb_private;
47 
48 char AppleObjCRuntime::ID = 0;
49 
50 AppleObjCRuntime::~AppleObjCRuntime() {}
51 
52 AppleObjCRuntime::AppleObjCRuntime(Process *process)
53     : ObjCLanguageRuntime(process), m_read_objc_library(false),
54       m_objc_trampoline_handler_up(), m_Foundation_major() {
55   ReadObjCLibraryIfNeeded(process->GetTarget().GetImages());
56 }
57 
58 bool AppleObjCRuntime::GetObjectDescription(Stream &str, ValueObject &valobj) {
59   CompilerType compiler_type(valobj.GetCompilerType());
60   bool is_signed;
61   // ObjC objects can only be pointers (or numbers that actually represents
62   // pointers but haven't been typecast, because reasons..)
63   if (!compiler_type.IsIntegerType(is_signed) && !compiler_type.IsPointerType())
64     return false;
65 
66   // Make the argument list: we pass one arg, the address of our pointer, to
67   // the print function.
68   Value val;
69 
70   if (!valobj.ResolveValue(val.GetScalar()))
71     return false;
72 
73   // Value Objects may not have a process in their ExecutionContextRef.  But we
74   // need to have one in the ref we pass down to eventually call description.
75   // Get it from the target if it isn't present.
76   ExecutionContext exe_ctx;
77   if (valobj.GetProcessSP()) {
78     exe_ctx = ExecutionContext(valobj.GetExecutionContextRef());
79   } else {
80     exe_ctx.SetContext(valobj.GetTargetSP(), true);
81     if (!exe_ctx.HasProcessScope())
82       return false;
83   }
84   return GetObjectDescription(str, val, exe_ctx.GetBestExecutionContextScope());
85 }
86 bool AppleObjCRuntime::GetObjectDescription(Stream &strm, Value &value,
87                                             ExecutionContextScope *exe_scope) {
88   if (!m_read_objc_library)
89     return false;
90 
91   ExecutionContext exe_ctx;
92   exe_scope->CalculateExecutionContext(exe_ctx);
93   Process *process = exe_ctx.GetProcessPtr();
94   if (!process)
95     return false;
96 
97   // We need other parts of the exe_ctx, but the processes have to match.
98   assert(m_process == process);
99 
100   // Get the function address for the print function.
101   const Address *function_address = GetPrintForDebuggerAddr();
102   if (!function_address)
103     return false;
104 
105   Target *target = exe_ctx.GetTargetPtr();
106   CompilerType compiler_type = value.GetCompilerType();
107   if (compiler_type) {
108     if (!ClangASTContext::IsObjCObjectPointerType(compiler_type)) {
109       strm.Printf("Value doesn't point to an ObjC object.\n");
110       return false;
111     }
112   } else {
113     // If it is not a pointer, see if we can make it into a pointer.
114     ClangASTContext *ast_context = target->GetScratchClangASTContext();
115     CompilerType opaque_type = ast_context->GetBasicType(eBasicTypeObjCID);
116     if (!opaque_type)
117       opaque_type = ast_context->GetBasicType(eBasicTypeVoid).GetPointerType();
118     // value.SetContext(Value::eContextTypeClangType, opaque_type_ptr);
119     value.SetCompilerType(opaque_type);
120   }
121 
122   ValueList arg_value_list;
123   arg_value_list.PushValue(value);
124 
125   // This is the return value:
126   ClangASTContext *ast_context = target->GetScratchClangASTContext();
127 
128   CompilerType return_compiler_type = ast_context->GetCStringType(true);
129   Value ret;
130   //    ret.SetContext(Value::eContextTypeClangType, return_compiler_type);
131   ret.SetCompilerType(return_compiler_type);
132 
133   if (exe_ctx.GetFramePtr() == nullptr) {
134     Thread *thread = exe_ctx.GetThreadPtr();
135     if (thread == nullptr) {
136       exe_ctx.SetThreadSP(process->GetThreadList().GetSelectedThread());
137       thread = exe_ctx.GetThreadPtr();
138     }
139     if (thread) {
140       exe_ctx.SetFrameSP(thread->GetSelectedFrame());
141     }
142   }
143 
144   // Now we're ready to call the function:
145 
146   DiagnosticManager diagnostics;
147   lldb::addr_t wrapper_struct_addr = LLDB_INVALID_ADDRESS;
148 
149   if (!m_print_object_caller_up) {
150     Status error;
151     m_print_object_caller_up.reset(
152         exe_scope->CalculateTarget()->GetFunctionCallerForLanguage(
153             eLanguageTypeObjC, return_compiler_type, *function_address,
154             arg_value_list, "objc-object-description", error));
155     if (error.Fail()) {
156       m_print_object_caller_up.reset();
157       strm.Printf("Could not get function runner to call print for debugger "
158                   "function: %s.",
159                   error.AsCString());
160       return false;
161     }
162     m_print_object_caller_up->InsertFunction(exe_ctx, wrapper_struct_addr,
163                                              diagnostics);
164   } else {
165     m_print_object_caller_up->WriteFunctionArguments(
166         exe_ctx, wrapper_struct_addr, arg_value_list, diagnostics);
167   }
168 
169   EvaluateExpressionOptions options;
170   options.SetUnwindOnError(true);
171   options.SetTryAllThreads(true);
172   options.SetStopOthers(true);
173   options.SetIgnoreBreakpoints(true);
174   options.SetTimeout(process->GetUtilityExpressionTimeout());
175   options.SetIsForUtilityExpr(true);
176 
177   ExpressionResults results = m_print_object_caller_up->ExecuteFunction(
178       exe_ctx, &wrapper_struct_addr, options, diagnostics, ret);
179   if (results != eExpressionCompleted) {
180     strm.Printf("Error evaluating Print Object function: %d.\n", results);
181     return false;
182   }
183 
184   addr_t result_ptr = ret.GetScalar().ULongLong(LLDB_INVALID_ADDRESS);
185 
186   char buf[512];
187   size_t cstr_len = 0;
188   size_t full_buffer_len = sizeof(buf) - 1;
189   size_t curr_len = full_buffer_len;
190   while (curr_len == full_buffer_len) {
191     Status error;
192     curr_len = process->ReadCStringFromMemory(result_ptr + cstr_len, buf,
193                                               sizeof(buf), error);
194     strm.Write(buf, curr_len);
195     cstr_len += curr_len;
196   }
197   return cstr_len > 0;
198 }
199 
200 lldb::ModuleSP AppleObjCRuntime::GetObjCModule() {
201   ModuleSP module_sp(m_objc_module_wp.lock());
202   if (module_sp)
203     return module_sp;
204 
205   Process *process = GetProcess();
206   if (process) {
207     const ModuleList &modules = process->GetTarget().GetImages();
208     for (uint32_t idx = 0; idx < modules.GetSize(); idx++) {
209       module_sp = modules.GetModuleAtIndex(idx);
210       if (AppleObjCRuntime::AppleIsModuleObjCLibrary(module_sp)) {
211         m_objc_module_wp = module_sp;
212         return module_sp;
213       }
214     }
215   }
216   return ModuleSP();
217 }
218 
219 Address *AppleObjCRuntime::GetPrintForDebuggerAddr() {
220   if (!m_PrintForDebugger_addr) {
221     const ModuleList &modules = m_process->GetTarget().GetImages();
222 
223     SymbolContextList contexts;
224     SymbolContext context;
225 
226     if ((!modules.FindSymbolsWithNameAndType(ConstString("_NSPrintForDebugger"),
227                                              eSymbolTypeCode, contexts)) &&
228         (!modules.FindSymbolsWithNameAndType(ConstString("_CFPrintForDebugger"),
229                                              eSymbolTypeCode, contexts)))
230       return nullptr;
231 
232     contexts.GetContextAtIndex(0, context);
233 
234     m_PrintForDebugger_addr.reset(new Address(context.symbol->GetAddress()));
235   }
236 
237   return m_PrintForDebugger_addr.get();
238 }
239 
240 bool AppleObjCRuntime::CouldHaveDynamicValue(ValueObject &in_value) {
241   return in_value.GetCompilerType().IsPossibleDynamicType(
242       nullptr,
243       false, // do not check C++
244       true); // check ObjC
245 }
246 
247 bool AppleObjCRuntime::GetDynamicTypeAndAddress(
248     ValueObject &in_value, lldb::DynamicValueType use_dynamic,
249     TypeAndOrName &class_type_or_name, Address &address,
250     Value::ValueType &value_type) {
251   return false;
252 }
253 
254 TypeAndOrName
255 AppleObjCRuntime::FixUpDynamicType(const TypeAndOrName &type_and_or_name,
256                                    ValueObject &static_value) {
257   CompilerType static_type(static_value.GetCompilerType());
258   Flags static_type_flags(static_type.GetTypeInfo());
259 
260   TypeAndOrName ret(type_and_or_name);
261   if (type_and_or_name.HasType()) {
262     // The type will always be the type of the dynamic object.  If our parent's
263     // type was a pointer, then our type should be a pointer to the type of the
264     // dynamic object.  If a reference, then the original type should be
265     // okay...
266     CompilerType orig_type = type_and_or_name.GetCompilerType();
267     CompilerType corrected_type = orig_type;
268     if (static_type_flags.AllSet(eTypeIsPointer))
269       corrected_type = orig_type.GetPointerType();
270     ret.SetCompilerType(corrected_type);
271   } else {
272     // If we are here we need to adjust our dynamic type name to include the
273     // correct & or * symbol
274     std::string corrected_name(type_and_or_name.GetName().GetCString());
275     if (static_type_flags.AllSet(eTypeIsPointer))
276       corrected_name.append(" *");
277     // the parent type should be a correctly pointer'ed or referenc'ed type
278     ret.SetCompilerType(static_type);
279     ret.SetName(corrected_name.c_str());
280   }
281   return ret;
282 }
283 
284 bool AppleObjCRuntime::AppleIsModuleObjCLibrary(const ModuleSP &module_sp) {
285   if (module_sp) {
286     const FileSpec &module_file_spec = module_sp->GetFileSpec();
287     static ConstString ObjCName("libobjc.A.dylib");
288 
289     if (module_file_spec) {
290       if (module_file_spec.GetFilename() == ObjCName)
291         return true;
292     }
293   }
294   return false;
295 }
296 
297 // we use the version of Foundation to make assumptions about the ObjC runtime
298 // on a target
299 uint32_t AppleObjCRuntime::GetFoundationVersion() {
300   if (!m_Foundation_major.hasValue()) {
301     const ModuleList &modules = m_process->GetTarget().GetImages();
302     for (uint32_t idx = 0; idx < modules.GetSize(); idx++) {
303       lldb::ModuleSP module_sp = modules.GetModuleAtIndex(idx);
304       if (!module_sp)
305         continue;
306       if (strcmp(module_sp->GetFileSpec().GetFilename().AsCString(""),
307                  "Foundation") == 0) {
308         m_Foundation_major = module_sp->GetVersion().getMajor();
309         return *m_Foundation_major;
310       }
311     }
312     return LLDB_INVALID_MODULE_VERSION;
313   } else
314     return m_Foundation_major.getValue();
315 }
316 
317 void AppleObjCRuntime::GetValuesForGlobalCFBooleans(lldb::addr_t &cf_true,
318                                                     lldb::addr_t &cf_false) {
319   cf_true = cf_false = LLDB_INVALID_ADDRESS;
320 }
321 
322 bool AppleObjCRuntime::IsModuleObjCLibrary(const ModuleSP &module_sp) {
323   return AppleIsModuleObjCLibrary(module_sp);
324 }
325 
326 bool AppleObjCRuntime::ReadObjCLibrary(const ModuleSP &module_sp) {
327   // Maybe check here and if we have a handler already, and the UUID of this
328   // module is the same as the one in the current module, then we don't have to
329   // reread it?
330   m_objc_trampoline_handler_up.reset(
331       new AppleObjCTrampolineHandler(m_process->shared_from_this(), module_sp));
332   if (m_objc_trampoline_handler_up != nullptr) {
333     m_read_objc_library = true;
334     return true;
335   } else
336     return false;
337 }
338 
339 ThreadPlanSP AppleObjCRuntime::GetStepThroughTrampolinePlan(Thread &thread,
340                                                             bool stop_others) {
341   ThreadPlanSP thread_plan_sp;
342   if (m_objc_trampoline_handler_up)
343     thread_plan_sp = m_objc_trampoline_handler_up->GetStepThroughDispatchPlan(
344         thread, stop_others);
345   return thread_plan_sp;
346 }
347 
348 // Static Functions
349 ObjCLanguageRuntime::ObjCRuntimeVersions
350 AppleObjCRuntime::GetObjCVersion(Process *process, ModuleSP &objc_module_sp) {
351   if (!process)
352     return ObjCRuntimeVersions::eObjC_VersionUnknown;
353 
354   Target &target = process->GetTarget();
355   if (target.GetArchitecture().GetTriple().getVendor() !=
356       llvm::Triple::VendorType::Apple)
357     return ObjCRuntimeVersions::eObjC_VersionUnknown;
358 
359   const ModuleList &target_modules = target.GetImages();
360   std::lock_guard<std::recursive_mutex> gaurd(target_modules.GetMutex());
361 
362   size_t num_images = target_modules.GetSize();
363   for (size_t i = 0; i < num_images; i++) {
364     ModuleSP module_sp = target_modules.GetModuleAtIndexUnlocked(i);
365     // One tricky bit here is that we might get called as part of the initial
366     // module loading, but before all the pre-run libraries get winnowed from
367     // the module list.  So there might actually be an old and incorrect ObjC
368     // library sitting around in the list, and we don't want to look at that.
369     // That's why we call IsLoadedInTarget.
370 
371     if (AppleIsModuleObjCLibrary(module_sp) &&
372         module_sp->IsLoadedInTarget(&target)) {
373       objc_module_sp = module_sp;
374       ObjectFile *ofile = module_sp->GetObjectFile();
375       if (!ofile)
376         return ObjCRuntimeVersions::eObjC_VersionUnknown;
377 
378       SectionList *sections = module_sp->GetSectionList();
379       if (!sections)
380         return ObjCRuntimeVersions::eObjC_VersionUnknown;
381       SectionSP v1_telltale_section_sp =
382           sections->FindSectionByName(ConstString("__OBJC"));
383       if (v1_telltale_section_sp) {
384         return ObjCRuntimeVersions::eAppleObjC_V1;
385       }
386       return ObjCRuntimeVersions::eAppleObjC_V2;
387     }
388   }
389 
390   return ObjCRuntimeVersions::eObjC_VersionUnknown;
391 }
392 
393 void AppleObjCRuntime::SetExceptionBreakpoints() {
394   const bool catch_bp = false;
395   const bool throw_bp = true;
396   const bool is_internal = true;
397 
398   if (!m_objc_exception_bp_sp) {
399     m_objc_exception_bp_sp = LanguageRuntime::CreateExceptionBreakpoint(
400         m_process->GetTarget(), GetLanguageType(), catch_bp, throw_bp,
401         is_internal);
402     if (m_objc_exception_bp_sp)
403       m_objc_exception_bp_sp->SetBreakpointKind("ObjC exception");
404   } else
405     m_objc_exception_bp_sp->SetEnabled(true);
406 }
407 
408 void AppleObjCRuntime::ClearExceptionBreakpoints() {
409   if (!m_process)
410     return;
411 
412   if (m_objc_exception_bp_sp.get()) {
413     m_objc_exception_bp_sp->SetEnabled(false);
414   }
415 }
416 
417 bool AppleObjCRuntime::ExceptionBreakpointsAreSet() {
418   return m_objc_exception_bp_sp && m_objc_exception_bp_sp->IsEnabled();
419 }
420 
421 bool AppleObjCRuntime::ExceptionBreakpointsExplainStop(
422     lldb::StopInfoSP stop_reason) {
423   if (!m_process)
424     return false;
425 
426   if (!stop_reason || stop_reason->GetStopReason() != eStopReasonBreakpoint)
427     return false;
428 
429   uint64_t break_site_id = stop_reason->GetValue();
430   return m_process->GetBreakpointSiteList().BreakpointSiteContainsBreakpoint(
431       break_site_id, m_objc_exception_bp_sp->GetID());
432 }
433 
434 bool AppleObjCRuntime::CalculateHasNewLiteralsAndIndexing() {
435   if (!m_process)
436     return false;
437 
438   Target &target(m_process->GetTarget());
439 
440   static ConstString s_method_signature(
441       "-[NSDictionary objectForKeyedSubscript:]");
442   static ConstString s_arclite_method_signature(
443       "__arclite_objectForKeyedSubscript");
444 
445   SymbolContextList sc_list;
446 
447   return target.GetImages().FindSymbolsWithNameAndType(
448              s_method_signature, eSymbolTypeCode, sc_list) ||
449          target.GetImages().FindSymbolsWithNameAndType(
450              s_arclite_method_signature, eSymbolTypeCode, sc_list);
451 }
452 
453 lldb::SearchFilterSP AppleObjCRuntime::CreateExceptionSearchFilter() {
454   Target &target = m_process->GetTarget();
455 
456   FileSpecList filter_modules;
457   if (target.GetArchitecture().GetTriple().getVendor() == llvm::Triple::Apple) {
458     filter_modules.Append(std::get<0>(GetExceptionThrowLocation()));
459   }
460   return target.GetSearchFilterForModuleList(&filter_modules);
461 }
462 
463 ValueObjectSP AppleObjCRuntime::GetExceptionObjectForThread(
464     ThreadSP thread_sp) {
465   auto *cpp_runtime = m_process->GetLanguageRuntime(eLanguageTypeC_plus_plus);
466   if (!cpp_runtime) return ValueObjectSP();
467   auto cpp_exception = cpp_runtime->GetExceptionObjectForThread(thread_sp);
468   if (!cpp_exception) return ValueObjectSP();
469 
470   auto descriptor = GetClassDescriptor(*cpp_exception);
471   if (!descriptor || !descriptor->IsValid()) return ValueObjectSP();
472 
473   while (descriptor) {
474     ConstString class_name(descriptor->GetClassName());
475     if (class_name == "NSException")
476       return cpp_exception;
477     descriptor = descriptor->GetSuperclass();
478   }
479 
480   return ValueObjectSP();
481 }
482 
483 ThreadSP AppleObjCRuntime::GetBacktraceThreadFromException(
484     lldb::ValueObjectSP exception_sp) {
485   ValueObjectSP reserved_dict =
486       exception_sp->GetChildMemberWithName(ConstString("reserved"), true);
487   if (!reserved_dict) return ThreadSP();
488 
489   reserved_dict = reserved_dict->GetSyntheticValue();
490   if (!reserved_dict) return ThreadSP();
491 
492   CompilerType objc_id =
493       exception_sp->GetTargetSP()->GetScratchClangASTContext()->GetBasicType(
494           lldb::eBasicTypeObjCID);
495   ValueObjectSP return_addresses;
496 
497   auto objc_object_from_address = [&exception_sp, &objc_id](uint64_t addr,
498                                                             const char *name) {
499     Value value(addr);
500     value.SetCompilerType(objc_id);
501     auto object = ValueObjectConstResult::Create(
502         exception_sp->GetTargetSP().get(), value, ConstString(name));
503     object = object->GetDynamicValue(eDynamicDontRunTarget);
504     return object;
505   };
506 
507   for (size_t idx = 0; idx < reserved_dict->GetNumChildren(); idx++) {
508     ValueObjectSP dict_entry = reserved_dict->GetChildAtIndex(idx, true);
509 
510     DataExtractor data;
511     data.SetAddressByteSize(dict_entry->GetProcessSP()->GetAddressByteSize());
512     Status error;
513     dict_entry->GetData(data, error);
514     if (error.Fail()) return ThreadSP();
515 
516     lldb::offset_t data_offset = 0;
517     auto dict_entry_key = data.GetPointer(&data_offset);
518     auto dict_entry_value = data.GetPointer(&data_offset);
519 
520     auto key_nsstring = objc_object_from_address(dict_entry_key, "key");
521     StreamString key_summary;
522     if (lldb_private::formatters::NSStringSummaryProvider(
523             *key_nsstring, key_summary, TypeSummaryOptions()) &&
524         !key_summary.Empty()) {
525       if (key_summary.GetString() == "\"callStackReturnAddresses\"") {
526         return_addresses = objc_object_from_address(dict_entry_value,
527                                                     "callStackReturnAddresses");
528         break;
529       }
530     }
531   }
532 
533   if (!return_addresses) return ThreadSP();
534   auto frames_value =
535       return_addresses->GetChildMemberWithName(ConstString("_frames"), true);
536   addr_t frames_addr = frames_value->GetValueAsUnsigned(0);
537   auto count_value =
538       return_addresses->GetChildMemberWithName(ConstString("_cnt"), true);
539   size_t count = count_value->GetValueAsUnsigned(0);
540   auto ignore_value =
541       return_addresses->GetChildMemberWithName(ConstString("_ignore"), true);
542   size_t ignore = ignore_value->GetValueAsUnsigned(0);
543 
544   size_t ptr_size = m_process->GetAddressByteSize();
545   std::vector<lldb::addr_t> pcs;
546   for (size_t idx = 0; idx < count; idx++) {
547     Status error;
548     addr_t pc = m_process->ReadPointerFromMemory(
549         frames_addr + (ignore + idx) * ptr_size, error);
550     pcs.push_back(pc);
551   }
552 
553   if (pcs.empty()) return ThreadSP();
554 
555   ThreadSP new_thread_sp(new HistoryThread(*m_process, 0, pcs));
556   m_process->GetExtendedThreadList().AddThread(new_thread_sp);
557   return new_thread_sp;
558 }
559 
560 std::tuple<FileSpec, ConstString>
561 AppleObjCRuntime::GetExceptionThrowLocation() {
562   return std::make_tuple(
563       FileSpec("libobjc.A.dylib"), ConstString("objc_exception_throw"));
564 }
565 
566 void AppleObjCRuntime::ReadObjCLibraryIfNeeded(const ModuleList &module_list) {
567   if (!HasReadObjCLibrary()) {
568     std::lock_guard<std::recursive_mutex> guard(module_list.GetMutex());
569 
570     size_t num_modules = module_list.GetSize();
571     for (size_t i = 0; i < num_modules; i++) {
572       auto mod = module_list.GetModuleAtIndex(i);
573       if (IsModuleObjCLibrary(mod)) {
574         ReadObjCLibrary(mod);
575         break;
576       }
577     }
578   }
579 }
580 
581 void AppleObjCRuntime::ModulesDidLoad(const ModuleList &module_list) {
582   ReadObjCLibraryIfNeeded(module_list);
583 }
584