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ladybird/Libraries/LibJS/Runtime/ProxyObject.cpp
Linus Groh 9ea6ef4ed1 LibJS: Make Interpreter::throw_exception() a void function 
The motivation for this change is twofold:

- Returning a JS::Value is misleading as one would expect it to carry
  some meaningful information, like maybe the error object that's being
  created, but in fact it is always empty. Supposedly to serve as a
  shortcut for the common case of "throw and return empty value", but
  that's just leading us to my second point.
- Inconsistent usage / coding style: as of this commit there are 114
  uses of throw_exception() discarding its return value and 55 uses
  directly returning the call result (in LibJS, not counting LibWeb);
  with the first style often having a more explicit empty value (or
  nullptr in some cases) return anyway.
  One more line to always make the return value obvious is should be
  worth it.

So now it's basically always these steps, which is already being used in
the majority of cases (as outlined above):

- Throw an exception. This mutates interpreter state by updating
  m_exception and unwinding, but doesn't return anything.
- Let the caller explicitly return an empty value, nullptr or anything
  else itself.
2020-08-25 18:30:31 +02:00

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/*
* Copyright (c) 2020, Matthew Olsson <matthewcolsson@gmail.com>
* All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions are met:
*
* 1. Redistributions of source code must retain the above copyright notice, this
* list of conditions and the following disclaimer.
*
* 2. Redistributions in binary form must reproduce the above copyright notice,
* this list of conditions and the following disclaimer in the documentation
* and/or other materials provided with the distribution.
*
* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
* AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
* DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE
* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
* SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
* CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
* OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
* OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
*/
#include <LibJS/Interpreter.h>
#include <LibJS/Runtime/Accessor.h>
#include <LibJS/Runtime/Array.h>
#include <LibJS/Runtime/Error.h>
#include <LibJS/Runtime/GlobalObject.h>
#include <LibJS/Runtime/ProxyObject.h>
namespace JS {
bool static is_compatible_property_descriptor(Interpreter& interpreter, bool is_extensible, PropertyDescriptor new_descriptor, Optional<PropertyDescriptor> current_descriptor_optional)
{
if (!current_descriptor_optional.has_value())
return is_extensible;
auto current_descriptor = current_descriptor_optional.value();
if (new_descriptor.attributes.is_empty() && new_descriptor.value.is_empty() && !new_descriptor.getter && !new_descriptor.setter)
return true;
if (!current_descriptor.attributes.is_configurable()) {
if (new_descriptor.attributes.is_configurable())
return false;
if (new_descriptor.attributes.has_enumerable() && new_descriptor.attributes.is_enumerable() != current_descriptor.attributes.is_enumerable())
return false;
}
if (new_descriptor.is_generic_descriptor())
return true;
if (current_descriptor.is_data_descriptor() != new_descriptor.is_data_descriptor() && !current_descriptor.attributes.is_configurable())
return false;
if (current_descriptor.is_data_descriptor() && new_descriptor.is_data_descriptor() && !current_descriptor.attributes.is_configurable() && !current_descriptor.attributes.is_writable()) {
if (new_descriptor.attributes.is_writable())
return false;
return new_descriptor.value.is_empty() && same_value(interpreter, new_descriptor.value, current_descriptor.value);
}
return true;
}
ProxyObject* ProxyObject::create(GlobalObject& global_object, Object& target, Object& handler)
{
return global_object.heap().allocate<ProxyObject>(global_object, target, handler, *global_object.proxy_prototype());
}
ProxyObject::ProxyObject(Object& target, Object& handler, Object& prototype)
: Function(prototype)
, m_target(target)
, m_handler(handler)
{
}
ProxyObject::~ProxyObject()
{
}
Object* ProxyObject::prototype()
{
if (m_is_revoked) {
interpreter().throw_exception<TypeError>(ErrorType::ProxyRevoked);
return nullptr;
}
auto trap = m_handler.get("getPrototypeOf");
if (interpreter().exception())
return nullptr;
if (trap.is_empty() || trap.is_undefined() || trap.is_null())
return m_target.prototype();
if (!trap.is_function()) {
interpreter().throw_exception<TypeError>(ErrorType::ProxyInvalidTrap, "getPrototypeOf");
return nullptr;
}
MarkedValueList arguments(interpreter().heap());
arguments.append(Value(&m_target));
auto trap_result = interpreter().call(trap.as_function(), Value(&m_handler), move(arguments));
if (interpreter().exception())
return nullptr;
if (!trap_result.is_object() && !trap_result.is_null()) {
interpreter().throw_exception<TypeError>(ErrorType::ProxyGetPrototypeOfReturn);
return nullptr;
}
if (m_target.is_extensible()) {
if (interpreter().exception())
return nullptr;
if (trap_result.is_null())
return nullptr;
return &trap_result.as_object();
}
auto target_proto = m_target.prototype();
if (interpreter().exception())
return nullptr;
if (!same_value(interpreter(), trap_result, Value(target_proto))) {
interpreter().throw_exception<TypeError>(ErrorType::ProxyGetPrototypeOfNonExtensible);
return nullptr;
}
return &trap_result.as_object();
}
const Object* ProxyObject::prototype() const
{
if (m_is_revoked) {
interpreter().throw_exception<TypeError>(ErrorType::ProxyRevoked);
return nullptr;
}
return const_cast<const Object*>(const_cast<ProxyObject*>(this)->prototype());
}
bool ProxyObject::set_prototype(Object* object)
{
if (m_is_revoked) {
interpreter().throw_exception<TypeError>(ErrorType::ProxyRevoked);
return false;
}
auto trap = m_handler.get("setPrototypeOf");
if (interpreter().exception())
return false;
if (trap.is_empty() || trap.is_undefined() || trap.is_null())
return m_target.set_prototype(object);
if (!trap.is_function()) {
interpreter().throw_exception<TypeError>(ErrorType::ProxyInvalidTrap, "setPrototypeOf");
return false;
}
MarkedValueList arguments(interpreter().heap());
arguments.append(Value(&m_target));
arguments.append(Value(object));
auto trap_result = interpreter().call(trap.as_function(), Value(&m_handler), move(arguments)).to_boolean();
if (interpreter().exception() || !trap_result)
return false;
if (m_target.is_extensible())
return true;
auto* target_proto = m_target.prototype();
if (interpreter().exception())
return false;
if (!same_value(interpreter(), Value(object), Value(target_proto))) {
interpreter().throw_exception<TypeError>(ErrorType::ProxySetPrototypeOfNonExtensible);
return false;
}
return true;
}
bool ProxyObject::is_extensible() const
{
if (m_is_revoked) {
interpreter().throw_exception<TypeError>(ErrorType::ProxyRevoked);
return false;
}
auto trap = m_handler.get("isExtensible");
if (interpreter().exception())
return false;
if (trap.is_empty() || trap.is_undefined() || trap.is_null())
return m_target.is_extensible();
if (!trap.is_function()) {
interpreter().throw_exception<TypeError>(ErrorType::ProxyInvalidTrap, "isExtensible");
return {};
}
MarkedValueList arguments(interpreter().heap());
arguments.append(Value(&m_target));
auto trap_result = interpreter().call(trap.as_function(), Value(&m_handler), move(arguments)).to_boolean();
if (interpreter().exception())
return false;
if (trap_result != m_target.is_extensible()) {
if (!interpreter().exception())
interpreter().throw_exception<TypeError>(ErrorType::ProxyIsExtensibleReturn);
return false;
}
return trap_result;
}
bool ProxyObject::prevent_extensions()
{
if (m_is_revoked) {
interpreter().throw_exception<TypeError>(ErrorType::ProxyRevoked);
return false;
}
auto trap = m_handler.get("preventExtensions");
if (interpreter().exception())
return false;
if (trap.is_empty() || trap.is_undefined() || trap.is_null())
return m_target.prevent_extensions();
if (!trap.is_function()) {
interpreter().throw_exception<TypeError>(ErrorType::ProxyInvalidTrap, "preventExtensions");
return {};
}
MarkedValueList arguments(interpreter().heap());
arguments.append(Value(&m_target));
auto trap_result = interpreter().call(trap.as_function(), Value(&m_handler), move(arguments)).to_boolean();
if (interpreter().exception())
return false;
if (trap_result && m_target.is_extensible()) {
if (!interpreter().exception())
interpreter().throw_exception<TypeError>(ErrorType::ProxyPreventExtensionsReturn);
return false;
}
return trap_result;
}
Optional<PropertyDescriptor> ProxyObject::get_own_property_descriptor(const PropertyName& name) const
{
if (m_is_revoked) {
interpreter().throw_exception<TypeError>(ErrorType::ProxyRevoked);
return {};
}
auto trap = m_handler.get("getOwnPropertyDescriptor");
if (interpreter().exception())
return {};
if (trap.is_empty() || trap.is_undefined() || trap.is_null())
return m_target.get_own_property_descriptor(name);
if (!trap.is_function()) {
interpreter().throw_exception<TypeError>(ErrorType::ProxyInvalidTrap, "getOwnPropertyDescriptor");
return {};
}
MarkedValueList arguments(interpreter().heap());
arguments.append(Value(&m_target));
arguments.append(js_string(interpreter(), name.to_string()));
auto trap_result = interpreter().call(trap.as_function(), Value(&m_handler), move(arguments));
if (interpreter().exception())
return {};
if (!trap_result.is_object() && !trap_result.is_undefined()) {
interpreter().throw_exception<TypeError>(ErrorType::ProxyGetOwnDescriptorReturn);
return {};
}
auto target_desc = m_target.get_own_property_descriptor(name);
if (interpreter().exception())
return {};
if (trap_result.is_undefined()) {
if (!target_desc.has_value())
return {};
if (!target_desc.value().attributes.is_configurable()) {
interpreter().throw_exception<TypeError>(ErrorType::ProxyGetOwnDescriptorNonConfigurable);
return {};
}
if (!m_target.is_extensible()) {
if (!interpreter().exception())
interpreter().throw_exception<TypeError>(ErrorType::ProxyGetOwnDescriptorUndefReturn);
return {};
}
return {};
}
auto result_desc = PropertyDescriptor::from_dictionary(interpreter(), trap_result.as_object());
if (interpreter().exception())
return {};
if (!is_compatible_property_descriptor(interpreter(), m_target.is_extensible(), result_desc, target_desc)) {
if (!interpreter().exception())
interpreter().throw_exception<TypeError>(ErrorType::ProxyGetOwnDescriptorInvalidDescriptor);
return {};
}
if (!result_desc.attributes.is_configurable() && (!target_desc.has_value() || target_desc.value().attributes.is_configurable())) {
interpreter().throw_exception<TypeError>(ErrorType::ProxyGetOwnDescriptorInvalidNonConfig);
return {};
}
return result_desc;
}
bool ProxyObject::define_property(const StringOrSymbol& property_name, const Object& descriptor, bool throw_exceptions)
{
if (m_is_revoked) {
interpreter().throw_exception<TypeError>(ErrorType::ProxyRevoked);
return false;
}
auto trap = m_handler.get("defineProperty");
if (interpreter().exception())
return false;
if (trap.is_empty() || trap.is_undefined() || trap.is_null())
return m_target.define_property(property_name, descriptor, throw_exceptions);
if (!trap.is_function()) {
interpreter().throw_exception<TypeError>(ErrorType::ProxyInvalidTrap, "defineProperty");
return false;
}
MarkedValueList arguments(interpreter().heap());
arguments.append(Value(&m_target));
arguments.append(property_name.to_value(interpreter()));
arguments.append(Value(const_cast<Object*>(&descriptor)));
auto trap_result = interpreter().call(trap.as_function(), Value(&m_handler), move(arguments)).to_boolean();
if (interpreter().exception() || !trap_result)
return false;
auto target_desc = m_target.get_own_property_descriptor(property_name);
if (interpreter().exception())
return false;
bool setting_config_false = false;
if (descriptor.has_property("configurable") && !descriptor.get("configurable").to_boolean())
setting_config_false = true;
if (interpreter().exception())
return false;
if (!target_desc.has_value()) {
if (!m_target.is_extensible()) {
if (!interpreter().exception())
interpreter().throw_exception<TypeError>(ErrorType::ProxyDefinePropNonExtensible);
return false;
}
if (setting_config_false) {
interpreter().throw_exception<TypeError>(ErrorType::ProxyDefinePropNonConfigurableNonExisting);
return false;
}
} else {
if (!is_compatible_property_descriptor(interpreter(), m_target.is_extensible(), PropertyDescriptor::from_dictionary(interpreter(), descriptor), target_desc)) {
if (!interpreter().exception())
interpreter().throw_exception<TypeError>(ErrorType::ProxyDefinePropIncompatibleDescriptor);
return false;
}
if (setting_config_false && target_desc.value().attributes.is_configurable()) {
interpreter().throw_exception<TypeError>(ErrorType::ProxyDefinePropExistingConfigurable);
return false;
}
}
return true;
}
bool ProxyObject::has_property(const PropertyName& name) const
{
if (m_is_revoked) {
interpreter().throw_exception<TypeError>(ErrorType::ProxyRevoked);
return false;
}
auto trap = m_handler.get("has");
if (interpreter().exception())
return false;
if (trap.is_empty() || trap.is_undefined() || trap.is_null())
return m_target.has_property(name);
if (!trap.is_function()) {
interpreter().throw_exception<TypeError>(ErrorType::ProxyInvalidTrap, "has");
return false;
}
MarkedValueList arguments(interpreter().heap());
arguments.append(Value(&m_target));
arguments.append(js_string(interpreter(), name.to_string()));
auto trap_result = interpreter().call(trap.as_function(), Value(&m_handler), move(arguments)).to_boolean();
if (interpreter().exception())
return false;
if (!trap_result) {
auto target_desc = m_target.get_own_property_descriptor(name);
if (interpreter().exception())
return false;
if (target_desc.has_value()) {
if (!target_desc.value().attributes.is_configurable()) {
interpreter().throw_exception<TypeError>(ErrorType::ProxyHasExistingNonConfigurable);
return false;
}
if (!m_target.is_extensible()) {
if (!interpreter().exception())
interpreter().throw_exception<TypeError>(ErrorType::ProxyHasExistingNonExtensible);
return false;
}
}
}
return trap_result;
}
Value ProxyObject::get(const PropertyName& name, Value) const
{
if (m_is_revoked) {
interpreter().throw_exception<TypeError>(ErrorType::ProxyRevoked);
return {};
}
auto trap = m_handler.get("get");
if (interpreter().exception())
return {};
if (trap.is_empty() || trap.is_undefined() || trap.is_null())
return m_target.get(name);
if (!trap.is_function()) {
interpreter().throw_exception<TypeError>(ErrorType::ProxyInvalidTrap, "get");
return {};
}
MarkedValueList arguments(interpreter().heap());
arguments.append(Value(&m_target));
arguments.append(js_string(interpreter(), name.to_string()));
arguments.append(Value(const_cast<ProxyObject*>(this)));
auto trap_result = interpreter().call(trap.as_function(), Value(&m_handler), move(arguments));
if (interpreter().exception())
return {};
auto target_desc = m_target.get_own_property_descriptor(name);
if (target_desc.has_value()) {
if (interpreter().exception())
return {};
if (target_desc.value().is_data_descriptor() && !target_desc.value().attributes.is_writable() && !same_value(interpreter(), trap_result, target_desc.value().value)) {
interpreter().throw_exception<TypeError>(ErrorType::ProxyGetImmutableDataProperty);
return {};
}
if (target_desc.value().is_accessor_descriptor() && target_desc.value().getter == nullptr && !trap_result.is_undefined()) {
interpreter().throw_exception<TypeError>(ErrorType::ProxyGetNonConfigurableAccessor);
return {};
}
}
return trap_result;
}
bool ProxyObject::put(const PropertyName& name, Value value, Value)
{
if (m_is_revoked) {
interpreter().throw_exception<TypeError>(ErrorType::ProxyRevoked);
return false;
}
auto trap = m_handler.get("set");
if (interpreter().exception())
return false;
if (trap.is_empty() || trap.is_undefined() || trap.is_null())
return m_target.put(name, value);
if (!trap.is_function()) {
interpreter().throw_exception<TypeError>(ErrorType::ProxyInvalidTrap, "set");
return false;
}
MarkedValueList arguments(interpreter().heap());
arguments.append(Value(&m_target));
arguments.append(js_string(interpreter(), name.to_string()));
arguments.append(value);
arguments.append(Value(const_cast<ProxyObject*>(this)));
auto trap_result = interpreter().call(trap.as_function(), Value(&m_handler), move(arguments)).to_boolean();
if (interpreter().exception() || !trap_result)
return false;
auto target_desc = m_target.get_own_property_descriptor(name);
if (interpreter().exception())
return false;
if (target_desc.has_value() && !target_desc.value().attributes.is_configurable()) {
if (target_desc.value().is_data_descriptor() && !target_desc.value().attributes.is_writable() && !same_value(interpreter(), value, target_desc.value().value)) {
interpreter().throw_exception<TypeError>(ErrorType::ProxySetImmutableDataProperty);
return false;
}
if (target_desc.value().is_accessor_descriptor() && !target_desc.value().setter) {
interpreter().throw_exception<TypeError>(ErrorType::ProxySetNonConfigurableAccessor);
}
}
return true;
}
Value ProxyObject::delete_property(const PropertyName& name)
{
if (m_is_revoked) {
interpreter().throw_exception<TypeError>(ErrorType::ProxyRevoked);
return {};
}
auto trap = m_handler.get("deleteProperty");
if (interpreter().exception())
return {};
if (trap.is_empty() || trap.is_undefined() || trap.is_null())
return m_target.delete_property(name);
if (!trap.is_function()) {
interpreter().throw_exception<TypeError>(ErrorType::ProxyInvalidTrap, "deleteProperty");
return {};
}
MarkedValueList arguments(interpreter().heap());
arguments.append(Value(&m_target));
arguments.append(js_string(interpreter(), name.to_string()));
auto trap_result = interpreter().call(trap.as_function(), Value(&m_handler), move(arguments)).to_boolean();
if (interpreter().exception())
return {};
if (!trap_result)
return Value(false);
auto target_desc = m_target.get_own_property_descriptor(name);
if (interpreter().exception())
return {};
if (!target_desc.has_value())
return Value(true);
if (!target_desc.value().attributes.is_configurable()) {
interpreter().throw_exception<TypeError>(ErrorType::ProxyDeleteNonConfigurable);
return {};
}
return Value(true);
}
void ProxyObject::visit_children(Cell::Visitor& visitor)
{
Function::visit_children(visitor);
visitor.visit(&m_target);
visitor.visit(&m_handler);
}
Value ProxyObject::call(Interpreter& interpreter)
{
if (!is_function()) {
interpreter.throw_exception<TypeError>(ErrorType::NotAFunction, Value(this).to_string_without_side_effects().characters());
return {};
}
if (m_is_revoked) {
interpreter.throw_exception<TypeError>(ErrorType::ProxyRevoked);
return {};
}
auto trap = m_handler.get("apply");
if (interpreter.exception())
return {};
if (trap.is_empty() || trap.is_undefined() || trap.is_null())
return static_cast<Function&>(m_target).call(interpreter);
if (!trap.is_function()) {
interpreter.throw_exception<TypeError>(ErrorType::ProxyInvalidTrap, "apply");
return {};
}
MarkedValueList arguments(interpreter.heap());
arguments.append(Value(&m_target));
arguments.append(Value(&m_handler));
// FIXME: Pass global object
auto arguments_array = Array::create(interpreter.global_object());
interpreter.for_each_argument([&](auto& argument) {
arguments_array->indexed_properties().append(argument);
});
arguments.append(arguments_array);
return interpreter.call(trap.as_function(), Value(&m_handler), move(arguments));
}
Value ProxyObject::construct(Interpreter& interpreter, Function& new_target)
{
if (!is_function()) {
interpreter.throw_exception<TypeError>(ErrorType::NotAConstructor, Value(this).to_string_without_side_effects().characters());
return {};
}
if (m_is_revoked) {
interpreter.throw_exception<TypeError>(ErrorType::ProxyRevoked);
return {};
}
auto trap = m_handler.get("construct");
if (interpreter.exception())
return {};
if (trap.is_empty() || trap.is_undefined() || trap.is_null())
return static_cast<Function&>(m_target).construct(interpreter, new_target);
if (!trap.is_function()) {
interpreter.throw_exception<TypeError>(ErrorType::ProxyInvalidTrap, "construct");
return {};
}
MarkedValueList arguments(interpreter.heap());
arguments.append(Value(&m_target));
auto arguments_array = Array::create(interpreter.global_object());
interpreter.for_each_argument([&](auto& argument) {
arguments_array->indexed_properties().append(argument);
});
arguments.append(arguments_array);
arguments.append(Value(&new_target));
auto result = interpreter.call(trap.as_function(), Value(&m_handler), move(arguments));
if (!result.is_object()) {
interpreter.throw_exception<TypeError>(ErrorType::ProxyConstructBadReturnType);
return {};
}
return result;
}
const FlyString& ProxyObject::name() const
{
ASSERT(is_function());
return static_cast<Function&>(m_target).name();
}
LexicalEnvironment* ProxyObject::create_environment()
{
ASSERT(is_function());
return static_cast<Function&>(m_target).create_environment();
}
}
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