1 //===-- ValueObjectDynamicValue.cpp ---------------------------------------===//
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 "lldb/Core/ValueObjectDynamicValue.h"
10 #include "lldb/Core/Value.h"
11 #include "lldb/Core/ValueObject.h"
12 #include "lldb/Symbol/CompilerType.h"
13 #include "lldb/Symbol/Type.h"
14 #include "lldb/Target/ExecutionContext.h"
15 #include "lldb/Target/LanguageRuntime.h"
16 #include "lldb/Target/Process.h"
17 #include "lldb/Target/Target.h"
18 #include "lldb/Utility/DataExtractor.h"
19 #include "lldb/Utility/LLDBLog.h"
20 #include "lldb/Utility/Log.h"
21 #include "lldb/Utility/Scalar.h"
22 #include "lldb/Utility/Status.h"
23 #include "lldb/lldb-types.h"
24 
25 #include <cstring>
26 #include <optional>
27 namespace lldb_private {
28 class Declaration;
29 }
30 
31 using namespace lldb_private;
32 
33 ValueObjectDynamicValue::ValueObjectDynamicValue(
34     ValueObject &parent, lldb::DynamicValueType use_dynamic)
35     : ValueObject(parent), m_address(), m_dynamic_type_info(),
36       m_use_dynamic(use_dynamic) {
37   SetName(parent.GetName());
38 }
39 
40 CompilerType ValueObjectDynamicValue::GetCompilerTypeImpl() {
41   const bool success = UpdateValueIfNeeded(false);
42   if (success) {
43     if (m_dynamic_type_info.HasType())
44       return m_value.GetCompilerType();
45     else
46       return m_parent->GetCompilerType();
47   }
48   return m_parent->GetCompilerType();
49 }
50 
51 ConstString ValueObjectDynamicValue::GetTypeName() {
52   const bool success = UpdateValueIfNeeded(false);
53   if (success) {
54     if (m_dynamic_type_info.HasName())
55       return m_dynamic_type_info.GetName();
56   }
57   return m_parent->GetTypeName();
58 }
59 
60 TypeImpl ValueObjectDynamicValue::GetTypeImpl() {
61   const bool success = UpdateValueIfNeeded(false);
62   if (success && m_type_impl.IsValid()) {
63     return m_type_impl;
64   }
65   return m_parent->GetTypeImpl();
66 }
67 
68 ConstString ValueObjectDynamicValue::GetQualifiedTypeName() {
69   const bool success = UpdateValueIfNeeded(false);
70   if (success) {
71     if (m_dynamic_type_info.HasName())
72       return m_dynamic_type_info.GetName();
73   }
74   return m_parent->GetQualifiedTypeName();
75 }
76 
77 ConstString ValueObjectDynamicValue::GetDisplayTypeName() {
78   const bool success = UpdateValueIfNeeded(false);
79   if (success) {
80     if (m_dynamic_type_info.HasType())
81       return GetCompilerType().GetDisplayTypeName();
82     if (m_dynamic_type_info.HasName())
83       return m_dynamic_type_info.GetName();
84   }
85   return m_parent->GetDisplayTypeName();
86 }
87 
88 size_t ValueObjectDynamicValue::CalculateNumChildren(uint32_t max) {
89   const bool success = UpdateValueIfNeeded(false);
90   if (success && m_dynamic_type_info.HasType()) {
91     ExecutionContext exe_ctx(GetExecutionContextRef());
92     auto children_count = GetCompilerType().GetNumChildren(true, &exe_ctx);
93     return children_count <= max ? children_count : max;
94   } else
95     return m_parent->GetNumChildren(max);
96 }
97 
98 std::optional<uint64_t> ValueObjectDynamicValue::GetByteSize() {
99   const bool success = UpdateValueIfNeeded(false);
100   if (success && m_dynamic_type_info.HasType()) {
101     ExecutionContext exe_ctx(GetExecutionContextRef());
102     return m_value.GetValueByteSize(nullptr, &exe_ctx);
103   } else
104     return m_parent->GetByteSize();
105 }
106 
107 lldb::ValueType ValueObjectDynamicValue::GetValueType() const {
108   return m_parent->GetValueType();
109 }
110 
111 bool ValueObjectDynamicValue::UpdateValue() {
112   SetValueIsValid(false);
113   m_error.Clear();
114 
115   if (!m_parent->UpdateValueIfNeeded(false)) {
116     // The dynamic value failed to get an error, pass the error along
117     if (m_error.Success() && m_parent->GetError().Fail())
118       m_error = m_parent->GetError();
119     return false;
120   }
121 
122   // Setting our type_sp to NULL will route everything back through our parent
123   // which is equivalent to not using dynamic values.
124   if (m_use_dynamic == lldb::eNoDynamicValues) {
125     m_dynamic_type_info.Clear();
126     return true;
127   }
128 
129   ExecutionContext exe_ctx(GetExecutionContextRef());
130   Target *target = exe_ctx.GetTargetPtr();
131   if (target) {
132     m_data.SetByteOrder(target->GetArchitecture().GetByteOrder());
133     m_data.SetAddressByteSize(target->GetArchitecture().GetAddressByteSize());
134   }
135 
136   // First make sure our Type and/or Address haven't changed:
137   Process *process = exe_ctx.GetProcessPtr();
138   if (!process)
139     return false;
140 
141   TypeAndOrName class_type_or_name;
142   Address dynamic_address;
143   bool found_dynamic_type = false;
144   Value::ValueType value_type;
145 
146   LanguageRuntime *runtime = nullptr;
147 
148   lldb::LanguageType known_type = m_parent->GetObjectRuntimeLanguage();
149   if (known_type != lldb::eLanguageTypeUnknown &&
150       known_type != lldb::eLanguageTypeC) {
151     runtime = process->GetLanguageRuntime(known_type);
152     if (auto *preferred_runtime =
153             runtime->GetPreferredLanguageRuntime(*m_parent)) {
154       // Try the preferred runtime first.
155       found_dynamic_type = preferred_runtime->GetDynamicTypeAndAddress(
156           *m_parent, m_use_dynamic, class_type_or_name, dynamic_address,
157           value_type);
158       if (found_dynamic_type)
159         // Set the operative `runtime` for later use in this function.
160         runtime = preferred_runtime;
161     }
162     if (!found_dynamic_type)
163       // Fallback to the runtime for `known_type`.
164       found_dynamic_type = runtime->GetDynamicTypeAndAddress(
165           *m_parent, m_use_dynamic, class_type_or_name, dynamic_address,
166           value_type);
167   } else {
168     runtime = process->GetLanguageRuntime(lldb::eLanguageTypeC_plus_plus);
169     if (runtime)
170       found_dynamic_type = runtime->GetDynamicTypeAndAddress(
171           *m_parent, m_use_dynamic, class_type_or_name, dynamic_address,
172           value_type);
173 
174     if (!found_dynamic_type) {
175       runtime = process->GetLanguageRuntime(lldb::eLanguageTypeObjC);
176       if (runtime)
177         found_dynamic_type = runtime->GetDynamicTypeAndAddress(
178             *m_parent, m_use_dynamic, class_type_or_name, dynamic_address,
179             value_type);
180     }
181   }
182 
183   // Getting the dynamic value may have run the program a bit, and so marked us
184   // as needing updating, but we really don't...
185 
186   m_update_point.SetUpdated();
187 
188   if (runtime && found_dynamic_type) {
189     if (class_type_or_name.HasType()) {
190       m_type_impl =
191           TypeImpl(m_parent->GetCompilerType(),
192                    runtime->FixUpDynamicType(class_type_or_name, *m_parent)
193                        .GetCompilerType());
194     } else {
195       m_type_impl.Clear();
196     }
197   } else {
198     m_type_impl.Clear();
199   }
200 
201   // If we don't have a dynamic type, set ourselves to be invalid and return
202   // false.  We used to try to produce a dynamic ValueObject that behaved "like"
203   // its parent, but that failed for ValueObjectConstResult, which is too
204   // complex a beast to try to emulate.  If we return an invalid ValueObject,
205   // clients will end up getting the static value instead, which behaves
206   // correctly.
207   if (!found_dynamic_type) {
208     if (m_dynamic_type_info)
209       SetValueDidChange(true);
210     ClearDynamicTypeInformation();
211     m_dynamic_type_info.Clear();
212     m_error.SetErrorString("no dynamic type found");
213     return false;
214   }
215 
216   Value old_value(m_value);
217 
218   Log *log = GetLog(LLDBLog::Types);
219 
220   bool has_changed_type = false;
221 
222   if (!m_dynamic_type_info) {
223     m_dynamic_type_info = class_type_or_name;
224     has_changed_type = true;
225   } else if (class_type_or_name != m_dynamic_type_info) {
226     // We are another type, we need to tear down our children...
227     m_dynamic_type_info = class_type_or_name;
228     SetValueDidChange(true);
229     has_changed_type = true;
230   }
231 
232   if (has_changed_type)
233     ClearDynamicTypeInformation();
234 
235   if (!m_address.IsValid() || m_address != dynamic_address) {
236     if (m_address.IsValid())
237       SetValueDidChange(true);
238 
239     // We've moved, so we should be fine...
240     m_address = dynamic_address;
241     lldb::TargetSP target_sp(GetTargetSP());
242     lldb::addr_t load_address = m_address.GetLoadAddress(target_sp.get());
243     m_value.GetScalar() = load_address;
244   }
245 
246   if (runtime)
247     m_dynamic_type_info =
248         runtime->FixUpDynamicType(m_dynamic_type_info, *m_parent);
249 
250   m_value.SetCompilerType(m_dynamic_type_info.GetCompilerType());
251 
252   m_value.SetValueType(value_type);
253 
254   if (has_changed_type && log)
255     LLDB_LOGF(log, "[%s %p] has a new dynamic type %s", GetName().GetCString(),
256               static_cast<void *>(this), GetTypeName().GetCString());
257 
258   if (m_address.IsValid() && m_dynamic_type_info) {
259     // The variable value is in the Scalar value inside the m_value. We can
260     // point our m_data right to it.
261     m_error = m_value.GetValueAsData(&exe_ctx, m_data, GetModule().get());
262     if (m_error.Success()) {
263       if (!CanProvideValue()) {
264         // this value object represents an aggregate type whose children have
265         // values, but this object does not. So we say we are changed if our
266         // location has changed.
267         SetValueDidChange(m_value.GetValueType() != old_value.GetValueType() ||
268                           m_value.GetScalar() != old_value.GetScalar());
269       }
270 
271       SetValueIsValid(true);
272       return true;
273     }
274   }
275 
276   // We get here if we've failed above...
277   SetValueIsValid(false);
278   return false;
279 }
280 
281 bool ValueObjectDynamicValue::IsInScope() { return m_parent->IsInScope(); }
282 
283 bool ValueObjectDynamicValue::SetValueFromCString(const char *value_str,
284                                                   Status &error) {
285   if (!UpdateValueIfNeeded(false)) {
286     error.SetErrorString("unable to read value");
287     return false;
288   }
289 
290   uint64_t my_value = GetValueAsUnsigned(UINT64_MAX);
291   uint64_t parent_value = m_parent->GetValueAsUnsigned(UINT64_MAX);
292 
293   if (my_value == UINT64_MAX || parent_value == UINT64_MAX) {
294     error.SetErrorString("unable to read value");
295     return false;
296   }
297 
298   // if we are at an offset from our parent, in order to set ourselves
299   // correctly we would need to change the new value so that it refers to the
300   // correct dynamic type. we choose not to deal with that - if anything more
301   // than a value overwrite is required, you should be using the expression
302   // parser instead of the value editing facility
303   if (my_value != parent_value) {
304     // but NULL'ing out a value should always be allowed
305     if (strcmp(value_str, "0")) {
306       error.SetErrorString(
307           "unable to modify dynamic value, use 'expression' command");
308       return false;
309     }
310   }
311 
312   bool ret_val = m_parent->SetValueFromCString(value_str, error);
313   SetNeedsUpdate();
314   return ret_val;
315 }
316 
317 bool ValueObjectDynamicValue::SetData(DataExtractor &data, Status &error) {
318   if (!UpdateValueIfNeeded(false)) {
319     error.SetErrorString("unable to read value");
320     return false;
321   }
322 
323   uint64_t my_value = GetValueAsUnsigned(UINT64_MAX);
324   uint64_t parent_value = m_parent->GetValueAsUnsigned(UINT64_MAX);
325 
326   if (my_value == UINT64_MAX || parent_value == UINT64_MAX) {
327     error.SetErrorString("unable to read value");
328     return false;
329   }
330 
331   // if we are at an offset from our parent, in order to set ourselves
332   // correctly we would need to change the new value so that it refers to the
333   // correct dynamic type. we choose not to deal with that - if anything more
334   // than a value overwrite is required, you should be using the expression
335   // parser instead of the value editing facility
336   if (my_value != parent_value) {
337     // but NULL'ing out a value should always be allowed
338     lldb::offset_t offset = 0;
339 
340     if (data.GetAddress(&offset) != 0) {
341       error.SetErrorString(
342           "unable to modify dynamic value, use 'expression' command");
343       return false;
344     }
345   }
346 
347   bool ret_val = m_parent->SetData(data, error);
348   SetNeedsUpdate();
349   return ret_val;
350 }
351 
352 void ValueObjectDynamicValue::SetPreferredDisplayLanguage(
353     lldb::LanguageType lang) {
354   this->ValueObject::SetPreferredDisplayLanguage(lang);
355   if (m_parent)
356     m_parent->SetPreferredDisplayLanguage(lang);
357 }
358 
359 lldb::LanguageType ValueObjectDynamicValue::GetPreferredDisplayLanguage() {
360   if (m_preferred_display_language == lldb::eLanguageTypeUnknown) {
361     if (m_parent)
362       return m_parent->GetPreferredDisplayLanguage();
363     return lldb::eLanguageTypeUnknown;
364   } else
365     return m_preferred_display_language;
366 }
367 
368 bool ValueObjectDynamicValue::IsSyntheticChildrenGenerated() {
369   if (m_parent)
370     return m_parent->IsSyntheticChildrenGenerated();
371   return false;
372 }
373 
374 void ValueObjectDynamicValue::SetSyntheticChildrenGenerated(bool b) {
375   if (m_parent)
376     m_parent->SetSyntheticChildrenGenerated(b);
377   this->ValueObject::SetSyntheticChildrenGenerated(b);
378 }
379 
380 bool ValueObjectDynamicValue::GetDeclaration(Declaration &decl) {
381   if (m_parent)
382     return m_parent->GetDeclaration(decl);
383 
384   return ValueObject::GetDeclaration(decl);
385 }
386 
387 uint64_t ValueObjectDynamicValue::GetLanguageFlags() {
388   if (m_parent)
389     return m_parent->GetLanguageFlags();
390   return this->ValueObject::GetLanguageFlags();
391 }
392 
393 void ValueObjectDynamicValue::SetLanguageFlags(uint64_t flags) {
394   if (m_parent)
395     m_parent->SetLanguageFlags(flags);
396   else
397     this->ValueObject::SetLanguageFlags(flags);
398 }
399