1 // Copyright 2020 the V8 project authors. All rights reserved.
2 // Use of this source code is governed by a BSD-style license that can be
3 // found in the LICENSE file.
4
5 #include "tools/v8windbg/src/local-variables.h"
6
7 #include <vector>
8
9 #include "tools/v8windbg/base/utilities.h"
10 #include "tools/v8windbg/src/object-inspection.h"
11 #include "tools/v8windbg/src/v8-debug-helper-interop.h"
12 #include "tools/v8windbg/src/v8windbg-extension.h"
13
V8LocalVariables(WRL::ComPtr<IModelPropertyAccessor> original,bool is_parameters)14 V8LocalVariables::V8LocalVariables(WRL::ComPtr<IModelPropertyAccessor> original,
15 bool is_parameters)
16 : original_(original), is_parameters_(is_parameters) {}
17 V8LocalVariables::~V8LocalVariables() = default;
18
GetValue(PCWSTR key,IModelObject * context,IModelObject ** value)19 IFACEMETHODIMP V8LocalVariables::GetValue(PCWSTR key, IModelObject* context,
20 IModelObject** value) noexcept {
21 // See if the frame can fetch locals based on symbols. If so, it's a normal
22 // C++ frame, so we can be done.
23 HRESULT original_hr = original_->GetValue(key, context, value);
24 if (SUCCEEDED(original_hr)) return original_hr;
25
26 // Next, try to find out about the instruction pointer. If it is within the V8
27 // module, or points to unknown space outside a module (generated code), then
28 // we're interested. Otherwise, we have nothing useful to do.
29 WRL::ComPtr<IModelObject> attributes;
30 RETURN_IF_FAIL(context->GetKeyValue(L"Attributes", &attributes, nullptr));
31 WRL::ComPtr<IModelObject> boxed_instruction_offset;
32 RETURN_IF_FAIL(attributes->GetKeyValue(L"InstructionOffset",
33 &boxed_instruction_offset, nullptr));
34 ULONG64 instruction_offset{};
35 RETURN_IF_FAIL(
36 UnboxULong64(boxed_instruction_offset.Get(), &instruction_offset));
37 WRL::ComPtr<IDebugHostSymbols> symbols;
38 RETURN_IF_FAIL(sp_debug_host.As(&symbols));
39 WRL::ComPtr<IDebugHostContext> host_context;
40 RETURN_IF_FAIL(sp_debug_host->GetCurrentContext(&host_context));
41 WRL::ComPtr<IDebugHostModule> module;
42 if (SUCCEEDED(symbols->FindModuleByLocation(host_context.Get(),
43 instruction_offset, &module))) {
44 Location module_base;
45 RETURN_IF_FAIL(module->GetBaseLocation(&module_base));
46 WRL::ComPtr<IDebugHostModule> v8_module =
47 Extension::Current()->GetV8Module(host_context);
48 if (v8_module == nullptr) {
49 // Anything in a module must not be in the V8 module if the V8 module
50 // doesn't exist.
51 return original_hr;
52 }
53 Location v8_base;
54 RETURN_IF_FAIL(v8_module->GetBaseLocation(&v8_base));
55 if (module_base != v8_base) {
56 // It's in a module, but not the one that contains V8.
57 return original_hr;
58 }
59 }
60
61 // Initialize an empty result object.
62 WRL::ComPtr<IModelObject> result;
63 RETURN_IF_FAIL(sp_data_model_manager->CreateSyntheticObject(
64 host_context.Get(), &result));
65 WRL::ComPtr<IModelObject> parent_model;
66 RETURN_IF_FAIL(sp_data_model_manager->AcquireNamedModel(
67 is_parameters_ ? L"Debugger.Models.Parameters"
68 : L"Debugger.Models.LocalVariables",
69 &parent_model));
70 RETURN_IF_FAIL(result->AddParentModel(parent_model.Get(), /*context=*/nullptr,
71 /*override=*/false));
72
73 if (is_parameters_) {
74 // We're not actually adding any parameters data yet; we just need it to not
75 // fail so that the locals pane displays the LocalVariables. The locals pane
76 // displays nothing if getting either LocalVariables or Parameters fails.
77 *value = result.Detach();
78 return S_OK;
79 }
80
81 // Get the stack and frame pointers for the current frame.
82 WRL::ComPtr<IModelObject> boxed_stack_offset;
83 RETURN_IF_FAIL(
84 attributes->GetKeyValue(L"StackOffset", &boxed_stack_offset, nullptr));
85 ULONG64 stack_offset{};
86 RETURN_IF_FAIL(UnboxULong64(boxed_stack_offset.Get(), &stack_offset));
87 WRL::ComPtr<IModelObject> boxed_frame_offset;
88 RETURN_IF_FAIL(
89 attributes->GetKeyValue(L"FrameOffset", &boxed_frame_offset, nullptr));
90 ULONG64 frame_offset{};
91 RETURN_IF_FAIL(UnboxULong64(boxed_frame_offset.Get(), &frame_offset));
92
93 // Eventually v8_debug_helper will provide some help here, but for now, just
94 // provide the option to view the whole stack frame as tagged data. It can
95 // be somewhat useful.
96 WRL::ComPtr<IDebugHostType> object_type =
97 Extension::Current()->GetV8ObjectType(host_context);
98 if (object_type == nullptr) {
99 // There's nothing useful to do if we can't find the symbol for
100 // v8::internal::Object.
101 return original_hr;
102 }
103 ULONG64 object_size{};
104 RETURN_IF_FAIL(object_type->GetSize(&object_size));
105 ULONG64 num_objects = (frame_offset - stack_offset) / object_size;
106 ArrayDimension dimensions[] = {
107 {/*start=*/0, /*length=*/num_objects, /*stride=*/object_size}};
108 WRL::ComPtr<IDebugHostType> object_array_type;
109 RETURN_IF_FAIL(object_type->CreateArrayOf(/*dimensions=*/1, dimensions,
110 &object_array_type));
111 WRL::ComPtr<IModelObject> array;
112 RETURN_IF_FAIL(sp_data_model_manager->CreateTypedObject(
113 host_context.Get(), stack_offset, object_array_type.Get(), &array));
114 RETURN_IF_FAIL(
115 result->SetKey(L"memory interpreted as Objects", array.Get(), nullptr));
116
117 std::vector<Property> properties = GetStackFrame(host_context, frame_offset);
118 for (const auto& prop : properties) {
119 WRL::ComPtr<IModelObject> property;
120 RETURN_IF_FAIL(GetModelForProperty(prop, host_context, &property));
121 result->SetKey(reinterpret_cast<const wchar_t*>(prop.name.c_str()),
122 property.Get(), nullptr);
123 }
124
125 *value = result.Detach();
126 return S_OK;
127 }
128
SetValue(PCWSTR key,IModelObject * context,IModelObject * value)129 IFACEMETHODIMP V8LocalVariables::SetValue(PCWSTR key, IModelObject* context,
130 IModelObject* value) noexcept {
131 return E_NOTIMPL;
132 }
133