1//===-- ValueObjectChild.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 "lldb/Core/ValueObjectChild.h"
10
11#include "lldb/Core/Value.h"
12#include "lldb/Symbol/CompilerType.h"
13#include "lldb/Target/ExecutionContext.h"
14#include "lldb/Target/Process.h"
15#include "lldb/Utility/Flags.h"
16#include "lldb/Utility/Scalar.h"
17#include "lldb/Utility/Status.h"
18#include "lldb/lldb-forward.h"
19
20#include <functional>
21#include <memory>
22#include <vector>
23
24#include <stdio.h>
25#include <string.h>
26
27using namespace lldb_private;
28
29ValueObjectChild::ValueObjectChild(
30    ValueObject &parent, const CompilerType &compiler_type,
31    ConstString name, uint64_t byte_size, int32_t byte_offset,
32    uint32_t bitfield_bit_size, uint32_t bitfield_bit_offset,
33    bool is_base_class, bool is_deref_of_parent,
34    AddressType child_ptr_or_ref_addr_type, uint64_t language_flags)
35    : ValueObject(parent), m_compiler_type(compiler_type),
36      m_byte_size(byte_size), m_byte_offset(byte_offset),
37      m_bitfield_bit_size(bitfield_bit_size),
38      m_bitfield_bit_offset(bitfield_bit_offset),
39      m_is_base_class(is_base_class), m_is_deref_of_parent(is_deref_of_parent),
40      m_can_update_with_invalid_exe_ctx() {
41  m_name = name;
42  SetAddressTypeOfChildren(child_ptr_or_ref_addr_type);
43  SetLanguageFlags(language_flags);
44}
45
46ValueObjectChild::~ValueObjectChild() {}
47
48lldb::ValueType ValueObjectChild::GetValueType() const {
49  return m_parent->GetValueType();
50}
51
52size_t ValueObjectChild::CalculateNumChildren(uint32_t max) {
53  ExecutionContext exe_ctx(GetExecutionContextRef());
54  auto children_count = GetCompilerType().GetNumChildren(true, &exe_ctx);
55  return children_count <= max ? children_count : max;
56}
57
58static void AdjustForBitfieldness(ConstString &name,
59                                  uint8_t bitfield_bit_size) {
60  if (name && bitfield_bit_size) {
61    const char *compiler_type_name = name.AsCString();
62    if (compiler_type_name) {
63      std::vector<char> bitfield_type_name(strlen(compiler_type_name) + 32, 0);
64      ::snprintf(&bitfield_type_name.front(), bitfield_type_name.size(),
65                 "%s:%u", compiler_type_name, bitfield_bit_size);
66      name.SetCString(&bitfield_type_name.front());
67    }
68  }
69}
70
71ConstString ValueObjectChild::GetTypeName() {
72  if (m_type_name.IsEmpty()) {
73    m_type_name = GetCompilerType().GetConstTypeName();
74    AdjustForBitfieldness(m_type_name, m_bitfield_bit_size);
75  }
76  return m_type_name;
77}
78
79ConstString ValueObjectChild::GetQualifiedTypeName() {
80  ConstString qualified_name = GetCompilerType().GetConstTypeName();
81  AdjustForBitfieldness(qualified_name, m_bitfield_bit_size);
82  return qualified_name;
83}
84
85ConstString ValueObjectChild::GetDisplayTypeName() {
86  ConstString display_name = GetCompilerType().GetDisplayTypeName();
87  AdjustForBitfieldness(display_name, m_bitfield_bit_size);
88  return display_name;
89}
90
91LazyBool ValueObjectChild::CanUpdateWithInvalidExecutionContext() {
92  if (m_can_update_with_invalid_exe_ctx.hasValue())
93    return m_can_update_with_invalid_exe_ctx.getValue();
94  if (m_parent) {
95    ValueObject *opinionated_parent =
96        m_parent->FollowParentChain([](ValueObject *valobj) -> bool {
97          return (valobj->CanUpdateWithInvalidExecutionContext() ==
98                  eLazyBoolCalculate);
99        });
100    if (opinionated_parent)
101      return (m_can_update_with_invalid_exe_ctx =
102                  opinionated_parent->CanUpdateWithInvalidExecutionContext())
103          .getValue();
104  }
105  return (m_can_update_with_invalid_exe_ctx =
106              this->ValueObject::CanUpdateWithInvalidExecutionContext())
107      .getValue();
108}
109
110bool ValueObjectChild::UpdateValue() {
111  m_error.Clear();
112  SetValueIsValid(false);
113  ValueObject *parent = m_parent;
114  if (parent) {
115    if (parent->UpdateValueIfNeeded(false)) {
116      m_value.SetCompilerType(GetCompilerType());
117
118      CompilerType parent_type(parent->GetCompilerType());
119      // Copy the parent scalar value and the scalar value type
120      m_value.GetScalar() = parent->GetValue().GetScalar();
121      Value::ValueType value_type = parent->GetValue().GetValueType();
122      m_value.SetValueType(value_type);
123
124      Flags parent_type_flags(parent_type.GetTypeInfo());
125      const bool is_instance_ptr_base =
126          ((m_is_base_class) &&
127           (parent_type_flags.AnySet(lldb::eTypeInstanceIsPointer)));
128
129      if (parent->GetCompilerType().ShouldTreatScalarValueAsAddress()) {
130        lldb::addr_t addr = parent->GetPointerValue();
131        m_value.GetScalar() = addr;
132
133        if (addr == LLDB_INVALID_ADDRESS) {
134          m_error.SetErrorString("parent address is invalid.");
135        } else if (addr == 0) {
136          m_error.SetErrorString("parent is NULL");
137        } else {
138          m_value.GetScalar() += m_byte_offset;
139          AddressType addr_type = parent->GetAddressTypeOfChildren();
140
141          switch (addr_type) {
142          case eAddressTypeFile: {
143            lldb::ProcessSP process_sp(GetProcessSP());
144            if (process_sp && process_sp->IsAlive())
145              m_value.SetValueType(Value::eValueTypeLoadAddress);
146            else
147              m_value.SetValueType(Value::eValueTypeFileAddress);
148          } break;
149          case eAddressTypeLoad:
150            m_value.SetValueType(is_instance_ptr_base
151                                     ? Value::eValueTypeScalar
152                                     : Value::eValueTypeLoadAddress);
153            break;
154          case eAddressTypeHost:
155            m_value.SetValueType(Value::eValueTypeHostAddress);
156            break;
157          case eAddressTypeInvalid:
158            // TODO: does this make sense?
159            m_value.SetValueType(Value::eValueTypeScalar);
160            break;
161          }
162        }
163      } else {
164        switch (value_type) {
165        case Value::eValueTypeLoadAddress:
166        case Value::eValueTypeFileAddress:
167        case Value::eValueTypeHostAddress: {
168          lldb::addr_t addr =
169              m_value.GetScalar().ULongLong(LLDB_INVALID_ADDRESS);
170          if (addr == LLDB_INVALID_ADDRESS) {
171            m_error.SetErrorString("parent address is invalid.");
172          } else if (addr == 0) {
173            m_error.SetErrorString("parent is NULL");
174          } else {
175            // Set this object's scalar value to the address of its value by
176            // adding its byte offset to the parent address
177            m_value.GetScalar() += GetByteOffset();
178
179            // If a bitfield doesn't fit into the child_byte_size'd
180            // window at child_byte_offset, move the window forward
181            // until it fits.  The problem here is that Value has no
182            // notion of bitfields and thus the Value's DataExtractor
183            // is sized like the bitfields CompilerType; a sequence of
184            // bitfields, however, can be larger than their underlying
185            // type.
186            if (m_bitfield_bit_offset) {
187              const bool thread_and_frame_only_if_stopped = true;
188              ExecutionContext exe_ctx(GetExecutionContextRef().Lock(
189                  thread_and_frame_only_if_stopped));
190              if (auto type_bit_size = GetCompilerType().GetBitSize(
191                      exe_ctx.GetBestExecutionContextScope())) {
192                uint64_t bitfield_end =
193                    m_bitfield_bit_size + m_bitfield_bit_offset;
194                if (bitfield_end > *type_bit_size) {
195                  uint64_t overhang_bytes =
196                      (bitfield_end - *type_bit_size + 7) / 8;
197                  m_value.GetScalar() += overhang_bytes;
198                  m_bitfield_bit_offset -= overhang_bytes * 8;
199                }
200              }
201            }
202          }
203        } break;
204
205        case Value::eValueTypeScalar:
206          // try to extract the child value from the parent's scalar value
207          {
208            Scalar scalar(m_value.GetScalar());
209            if (m_bitfield_bit_size)
210              scalar.ExtractBitfield(m_bitfield_bit_size,
211                                     m_bitfield_bit_offset);
212            else
213              scalar.ExtractBitfield(8 * m_byte_size, 8 * m_byte_offset);
214            m_value.GetScalar() = scalar;
215          }
216          break;
217        default:
218          m_error.SetErrorString("parent has invalid value.");
219          break;
220        }
221      }
222
223      if (m_error.Success()) {
224        const bool thread_and_frame_only_if_stopped = true;
225        ExecutionContext exe_ctx(
226            GetExecutionContextRef().Lock(thread_and_frame_only_if_stopped));
227        if (GetCompilerType().GetTypeInfo() & lldb::eTypeHasValue) {
228          Value &value = is_instance_ptr_base ? m_parent->GetValue() : m_value;
229          m_error =
230              value.GetValueAsData(&exe_ctx, m_data, GetModule().get());
231        } else {
232          m_error.Clear(); // No value so nothing to read...
233        }
234      }
235
236    } else {
237      m_error.SetErrorStringWithFormat("parent failed to evaluate: %s",
238                                       parent->GetError().AsCString());
239    }
240  } else {
241    m_error.SetErrorString("ValueObjectChild has a NULL parent ValueObject.");
242  }
243
244  return m_error.Success();
245}
246
247bool ValueObjectChild::IsInScope() {
248  ValueObject *root(GetRoot());
249  if (root)
250    return root->IsInScope();
251  return false;
252}
253