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// Copyright 2015 the V8 project authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.
#include "src/debug/debug-evaluate.h"
#include "src/accessors.h"
#include "src/contexts.h"
#include "src/debug/debug.h"
#include "src/debug/debug-frames.h"
#include "src/debug/debug-scopes.h"
#include "src/frames-inl.h"
#include "src/isolate-inl.h"
namespace v8 {
namespace internal {
static inline bool IsDebugContext(Isolate* isolate, Context* context) {
return context->native_context() == *isolate->debug()->debug_context();
}
MaybeHandle<Object> DebugEvaluate::Global(
Isolate* isolate, Handle<String> source, bool disable_break,
Handle<HeapObject> context_extension) {
// Handle the processing of break.
DisableBreak disable_break_scope(isolate->debug(), disable_break);
// Enter the top context from before the debugger was invoked.
SaveContext save(isolate);
SaveContext* top = &save;
while (top != NULL && IsDebugContext(isolate, *top->context())) {
top = top->prev();
}
if (top != NULL) isolate->set_context(*top->context());
// Get the native context now set to the top context from before the
// debugger was invoked.
Handle<Context> context = isolate->native_context();
Handle<JSObject> receiver(context->global_proxy());
Handle<SharedFunctionInfo> outer_info(context->closure()->shared(), isolate);
return Evaluate(isolate, outer_info, context, context_extension, receiver,
source);
}
MaybeHandle<Object> DebugEvaluate::Local(Isolate* isolate,
StackFrame::Id frame_id,
int inlined_jsframe_index,
Handle<String> source,
bool disable_break,
Handle<HeapObject> context_extension) {
// Handle the processing of break.
DisableBreak disable_break_scope(isolate->debug(), disable_break);
// Get the frame where the debugging is performed.
JavaScriptFrameIterator it(isolate, frame_id);
JavaScriptFrame* frame = it.frame();
// Traverse the saved contexts chain to find the active context for the
// selected frame.
SaveContext* save =
DebugFrameHelper::FindSavedContextForFrame(isolate, frame);
SaveContext savex(isolate);
isolate->set_context(*(save->context()));
// This is not a lot different than DebugEvaluate::Global, except that
// variables accessible by the function we are evaluating from are
// materialized and included on top of the native context. Changes to
// the materialized object are written back afterwards.
// Note that the native context is taken from the original context chain,
// which may not be the current native context of the isolate.
ContextBuilder context_builder(isolate, frame, inlined_jsframe_index);
if (isolate->has_pending_exception()) return MaybeHandle<Object>();
Handle<Context> context = context_builder.evaluation_context();
Handle<JSObject> receiver(context->global_proxy());
MaybeHandle<Object> maybe_result =
Evaluate(isolate, context_builder.outer_info(), context,
context_extension, receiver, source);
if (!maybe_result.is_null()) context_builder.UpdateValues();
return maybe_result;
}
// Compile and evaluate source for the given context.
MaybeHandle<Object> DebugEvaluate::Evaluate(
Isolate* isolate, Handle<SharedFunctionInfo> outer_info,
Handle<Context> context, Handle<HeapObject> context_extension,
Handle<Object> receiver, Handle<String> source) {
if (context_extension->IsJSObject()) {
Handle<JSObject> extension = Handle<JSObject>::cast(context_extension);
Handle<JSFunction> closure(context->closure(), isolate);
context = isolate->factory()->NewWithContext(closure, context, extension);
}
Handle<JSFunction> eval_fun;
ASSIGN_RETURN_ON_EXCEPTION(isolate, eval_fun,
Compiler::GetFunctionFromEval(
source, outer_info, context, SLOPPY,
NO_PARSE_RESTRICTION, RelocInfo::kNoPosition),
Object);
Handle<Object> result;
ASSIGN_RETURN_ON_EXCEPTION(
isolate, result, Execution::Call(isolate, eval_fun, receiver, 0, NULL),
Object);
// Skip the global proxy as it has no properties and always delegates to the
// real global object.
if (result->IsJSGlobalProxy()) {
PrototypeIterator iter(isolate, Handle<JSGlobalProxy>::cast(result));
// TODO(verwaest): This will crash when the global proxy is detached.
result = PrototypeIterator::GetCurrent<JSObject>(iter);
}
return result;
}
DebugEvaluate::ContextBuilder::ContextBuilder(Isolate* isolate,
JavaScriptFrame* frame,
int inlined_jsframe_index)
: isolate_(isolate),
frame_(frame),
inlined_jsframe_index_(inlined_jsframe_index) {
FrameInspector frame_inspector(frame, inlined_jsframe_index, isolate);
Handle<JSFunction> local_function =
Handle<JSFunction>::cast(frame_inspector.GetFunction());
Handle<Context> outer_context(local_function->context());
evaluation_context_ = outer_context;
outer_info_ = handle(local_function->shared());
Factory* factory = isolate->factory();
// To evaluate as if we were running eval at the point of the debug break,
// we reconstruct the context chain as follows:
// - To make stack-allocated variables visible, we materialize them and
// use a debug-evaluate context to wrap both the materialized object and
// the original context.
// - We use the original context chain from the function context to the
// native context.
// - Between the function scope and the native context, we only resolve
// variable names that the current function already uses. Only for these
// names we can be sure that they will be correctly resolved. For the
// rest, we only resolve to with, script, and native contexts. We use a
// whitelist to implement that.
// Context::Lookup has special handling for debug-evaluate contexts:
// - Look up in the materialized stack variables.
// - Look up in the original context.
// - Check the whitelist to find out whether to skip contexts during lookup.
const ScopeIterator::Option option = ScopeIterator::COLLECT_NON_LOCALS;
for (ScopeIterator it(isolate, &frame_inspector, option);
!it.Failed() && !it.Done(); it.Next()) {
ScopeIterator::ScopeType scope_type = it.Type();
if (scope_type == ScopeIterator::ScopeTypeLocal) {
DCHECK_EQ(FUNCTION_SCOPE, it.CurrentScopeInfo()->scope_type());
Handle<JSObject> materialized = factory->NewJSObjectWithNullProto();
Handle<Context> local_context =
it.HasContext() ? it.CurrentContext() : outer_context;
Handle<StringSet> non_locals = it.GetNonLocals();
MaterializeReceiver(materialized, local_context, local_function,
non_locals);
frame_inspector.MaterializeStackLocals(materialized, local_function);
MaterializeArgumentsObject(materialized, local_function);
ContextChainElement context_chain_element;
context_chain_element.scope_info = it.CurrentScopeInfo();
context_chain_element.materialized_object = materialized;
// Non-locals that are already being referenced by the current function
// are guaranteed to be correctly resolved.
context_chain_element.whitelist = non_locals;
if (it.HasContext()) {
context_chain_element.wrapped_context = it.CurrentContext();
}
context_chain_.Add(context_chain_element);
evaluation_context_ = outer_context;
break;
} else if (scope_type == ScopeIterator::ScopeTypeCatch ||
scope_type == ScopeIterator::ScopeTypeWith) {
ContextChainElement context_chain_element;
Handle<Context> current_context = it.CurrentContext();
if (!current_context->IsDebugEvaluateContext()) {
context_chain_element.wrapped_context = current_context;
}
context_chain_.Add(context_chain_element);
} else if (scope_type == ScopeIterator::ScopeTypeBlock) {
Handle<JSObject> materialized = factory->NewJSObjectWithNullProto();
frame_inspector.MaterializeStackLocals(materialized,
it.CurrentScopeInfo());
ContextChainElement context_chain_element;
context_chain_element.scope_info = it.CurrentScopeInfo();
context_chain_element.materialized_object = materialized;
if (it.HasContext()) {
context_chain_element.wrapped_context = it.CurrentContext();
}
context_chain_.Add(context_chain_element);
} else {
break;
}
}
for (int i = context_chain_.length() - 1; i >= 0; i--) {
evaluation_context_ = factory->NewDebugEvaluateContext(
evaluation_context_, context_chain_[i].materialized_object,
context_chain_[i].wrapped_context, context_chain_[i].whitelist);
}
}
void DebugEvaluate::ContextBuilder::UpdateValues() {
// TODO(yangguo): remove updating values.
for (int i = 0; i < context_chain_.length(); i++) {
ContextChainElement element = context_chain_[i];
if (!element.materialized_object.is_null()) {
// Write back potential changes to materialized stack locals to the stack.
FrameInspector(frame_, inlined_jsframe_index_, isolate_)
.UpdateStackLocalsFromMaterializedObject(element.materialized_object,
element.scope_info);
}
}
}
void DebugEvaluate::ContextBuilder::MaterializeArgumentsObject(
Handle<JSObject> target, Handle<JSFunction> function) {
// Do not materialize the arguments object for eval or top-level code.
// Skip if "arguments" is already taken.
if (!function->shared()->is_function()) return;
Maybe<bool> maybe = JSReceiver::HasOwnProperty(
target, isolate_->factory()->arguments_string());
DCHECK(maybe.IsJust());
if (maybe.FromJust()) return;
// FunctionGetArguments can't throw an exception.
Handle<JSObject> arguments = Accessors::FunctionGetArguments(function);
Handle<String> arguments_str = isolate_->factory()->arguments_string();
JSObject::SetOwnPropertyIgnoreAttributes(target, arguments_str, arguments,
NONE)
.Check();
}
void DebugEvaluate::ContextBuilder::MaterializeReceiver(
Handle<JSObject> target, Handle<Context> local_context,
Handle<JSFunction> local_function, Handle<StringSet> non_locals) {
Handle<Object> recv = isolate_->factory()->undefined_value();
Handle<String> name = isolate_->factory()->this_string();
if (non_locals->Has(name)) {
// 'this' is allocated in an outer context and is is already being
// referenced by the current function, so it can be correctly resolved.
return;
} else if (local_function->shared()->scope_info()->HasReceiver() &&
!frame_->receiver()->IsTheHole()) {
recv = handle(frame_->receiver(), isolate_);
}
JSObject::SetOwnPropertyIgnoreAttributes(target, name, recv, NONE).Check();
}
} // namespace internal
} // namespace v8