ladybird/Libraries/LibJS/Runtime/ProxyObject.cpp
Shannon Booth f87041bf3a LibGC+Everywhere: Factor out a LibGC from LibJS
Resulting in a massive rename across almost everywhere! Alongside the
namespace change, we now have the following names:

 * JS::NonnullGCPtr -> GC::Ref
 * JS::GCPtr -> GC::Ptr
 * JS::HeapFunction -> GC::Function
 * JS::CellImpl -> GC::Cell
 * JS::Handle -> GC::Root
2024-11-15 14:49:20 +01:00

908 lines
37 KiB
C++

/*
* Copyright (c) 2020, Matthew Olsson <mattco@serenityos.org>
* Copyright (c) 2021-2023, Linus Groh <linusg@serenityos.org>
*
* SPDX-License-Identifier: BSD-2-Clause
*/
#include <LibJS/Runtime/AbstractOperations.h>
#include <LibJS/Runtime/Accessor.h>
#include <LibJS/Runtime/Array.h>
#include <LibJS/Runtime/Error.h>
#include <LibJS/Runtime/GlobalObject.h>
#include <LibJS/Runtime/PropertyDescriptor.h>
#include <LibJS/Runtime/ProxyObject.h>
#include <LibJS/Runtime/ValueInlines.h>
namespace JS {
GC_DEFINE_ALLOCATOR(ProxyObject);
// NOTE: We can't rely on native stack overflows to catch infinite recursion in Proxy traps,
// since the compiler may decide to optimize tail/sibling calls into loops.
// So instead we keep track of the recursion depth and throw a TypeError if it exceeds a certain limit.
static int s_recursion_depth = 0;
struct RecursionDepthUpdater {
RecursionDepthUpdater() { ++s_recursion_depth; }
~RecursionDepthUpdater() { --s_recursion_depth; }
};
#define LIMIT_PROXY_RECURSION_DEPTH() \
RecursionDepthUpdater recursion_depth_updater; \
do { \
if (s_recursion_depth >= 10000) \
return vm().throw_completion<InternalError>(ErrorType::CallStackSizeExceeded); \
} while (0)
GC::Ref<ProxyObject> ProxyObject::create(Realm& realm, Object& target, Object& handler)
{
return realm.create<ProxyObject>(target, handler, realm.intrinsics().object_prototype());
}
ProxyObject::ProxyObject(Object& target, Object& handler, Object& prototype)
: FunctionObject(prototype, MayInterfereWithIndexedPropertyAccess::Yes)
, m_target(target)
, m_handler(handler)
{
}
static Value property_key_to_value(VM& vm, PropertyKey const& property_key)
{
if (property_key.is_symbol())
return property_key.as_symbol();
if (property_key.is_string())
return PrimitiveString::create(vm, property_key.as_string());
VERIFY(property_key.is_number());
return PrimitiveString::create(vm, ByteString::number(property_key.as_number()));
}
// 10.5.1 [[GetPrototypeOf]] ( ), https://tc39.es/ecma262/#sec-proxy-object-internal-methods-and-internal-slots-getprototypeof
ThrowCompletionOr<Object*> ProxyObject::internal_get_prototype_of() const
{
LIMIT_PROXY_RECURSION_DEPTH();
auto& vm = this->vm();
// 1. Let handler be O.[[ProxyHandler]].
// 2. If handler is null, throw a TypeError exception.
if (m_is_revoked)
return vm.throw_completion<TypeError>(ErrorType::ProxyRevoked);
// 3. Assert: Type(handler) is Object.
// 4. Let target be O.[[ProxyTarget]].
// 5. Let trap be ? GetMethod(handler, "getPrototypeOf").
auto trap = TRY(Value(m_handler).get_method(vm, vm.names.getPrototypeOf));
// 6. If trap is undefined, then
if (!trap) {
// a. Return ? target.[[GetPrototypeOf]]().
return TRY(m_target->internal_get_prototype_of());
}
// 7. Let handlerProto be ? Call(trap, handler, « target »).
auto handler_proto = TRY(call(vm, *trap, m_handler, m_target));
// 8. If Type(handlerProto) is neither Object nor Null, throw a TypeError exception.
if (!handler_proto.is_object() && !handler_proto.is_null())
return vm.throw_completion<TypeError>(ErrorType::ProxyGetPrototypeOfReturn);
// 9. Let extensibleTarget be ? IsExtensible(target).
auto extensible_target = TRY(m_target->is_extensible());
// 10. If extensibleTarget is true, return handlerProto.
if (extensible_target)
return handler_proto.is_null() ? nullptr : &handler_proto.as_object();
// 11. Let targetProto be ? target.[[GetPrototypeOf]]().
auto* target_proto = TRY(m_target->internal_get_prototype_of());
// 12. If SameValue(handlerProto, targetProto) is false, throw a TypeError exception.
if (!same_value(handler_proto, target_proto))
return vm.throw_completion<TypeError>(ErrorType::ProxyGetPrototypeOfNonExtensible);
// 13. Return handlerProto.
return handler_proto.is_null() ? nullptr : &handler_proto.as_object();
}
// 10.5.2 [[SetPrototypeOf]] ( V ), https://tc39.es/ecma262/#sec-proxy-object-internal-methods-and-internal-slots-setprototypeof-v
ThrowCompletionOr<bool> ProxyObject::internal_set_prototype_of(Object* prototype)
{
LIMIT_PROXY_RECURSION_DEPTH();
auto& vm = this->vm();
// 1. Let handler be O.[[ProxyHandler]].
// 2. If handler is null, throw a TypeError exception.
if (m_is_revoked)
return vm.throw_completion<TypeError>(ErrorType::ProxyRevoked);
// 3. Assert: Type(handler) is Object.
// 4. Let target be O.[[ProxyTarget]].
// 5. Let trap be ? GetMethod(handler, "setPrototypeOf").
auto trap = TRY(Value(m_handler).get_method(vm, vm.names.setPrototypeOf));
// 6. If trap is undefined, then
if (!trap) {
// a. Return ? target.[[SetPrototypeOf]](V).
return m_target->internal_set_prototype_of(prototype);
}
// 7. Let booleanTrapResult be ToBoolean(? Call(trap, handler, « target, V »)).
auto trap_result = TRY(call(vm, *trap, m_handler, m_target, prototype)).to_boolean();
// 8. If booleanTrapResult is false, return false.
if (!trap_result)
return false;
// 9. Let extensibleTarget be ? IsExtensible(target).
auto extensible_target = TRY(m_target->is_extensible());
// 10. If extensibleTarget is true, return true.
if (extensible_target)
return true;
// 11. Let targetProto be ? target.[[GetPrototypeOf]]().
auto* target_proto = TRY(m_target->internal_get_prototype_of());
// 12. If SameValue(V, targetProto) is false, throw a TypeError exception.
if (!same_value(prototype, target_proto))
return vm.throw_completion<TypeError>(ErrorType::ProxySetPrototypeOfNonExtensible);
// 13. Return true.
return true;
}
// 10.5.3 [[IsExtensible]] ( ), https://tc39.es/ecma262/#sec-proxy-object-internal-methods-and-internal-slots-isextensible
ThrowCompletionOr<bool> ProxyObject::internal_is_extensible() const
{
LIMIT_PROXY_RECURSION_DEPTH();
auto& vm = this->vm();
// 1. Let handler be O.[[ProxyHandler]].
// 2. If handler is null, throw a TypeError exception.
if (m_is_revoked)
return vm.throw_completion<TypeError>(ErrorType::ProxyRevoked);
// 3. Assert: Type(handler) is Object.
// 4. Let target be O.[[ProxyTarget]].
// 5. Let trap be ? GetMethod(handler, "isExtensible").
auto trap = TRY(Value(m_handler).get_method(vm, vm.names.isExtensible));
// 6. If trap is undefined, then
if (!trap) {
// a. Return ? IsExtensible(target).
return m_target->is_extensible();
}
// 7. Let booleanTrapResult be ToBoolean(? Call(trap, handler, « target »)).
auto trap_result = TRY(call(vm, *trap, m_handler, m_target)).to_boolean();
// 8. Let targetResult be ? IsExtensible(target).
auto target_result = TRY(m_target->is_extensible());
// 9. If SameValue(booleanTrapResult, targetResult) is false, throw a TypeError exception.
if (trap_result != target_result)
return vm.throw_completion<TypeError>(ErrorType::ProxyIsExtensibleReturn);
// 10. Return booleanTrapResult.
return trap_result;
}
// 10.5.4 [[PreventExtensions]] ( ), https://tc39.es/ecma262/#sec-proxy-object-internal-methods-and-internal-slots-preventextensions
ThrowCompletionOr<bool> ProxyObject::internal_prevent_extensions()
{
LIMIT_PROXY_RECURSION_DEPTH();
auto& vm = this->vm();
// 1. Let handler be O.[[ProxyHandler]].
// 2. If handler is null, throw a TypeError exception.
if (m_is_revoked)
return vm.throw_completion<TypeError>(ErrorType::ProxyRevoked);
// 3. Assert: Type(handler) is Object.
// 4. Let target be O.[[ProxyTarget]].
// 5. Let trap be ? GetMethod(handler, "preventExtensions").
auto trap = TRY(Value(m_handler).get_method(vm, vm.names.preventExtensions));
// 6. If trap is undefined, then
if (!trap) {
// a. Return ? target.[[PreventExtensions]]().
return m_target->internal_prevent_extensions();
}
// 7. Let booleanTrapResult be ToBoolean(? Call(trap, handler, « target »)).
auto trap_result = TRY(call(vm, *trap, m_handler, m_target)).to_boolean();
// 8. If booleanTrapResult is true, then
if (trap_result) {
// a. Let extensibleTarget be ? IsExtensible(target).
auto extensible_target = TRY(m_target->is_extensible());
// b. If extensibleTarget is true, throw a TypeError exception.
if (extensible_target)
return vm.throw_completion<TypeError>(ErrorType::ProxyPreventExtensionsReturn);
}
// 9. Return booleanTrapResult.
return trap_result;
}
// 10.5.5 [[GetOwnProperty]] ( P ), https://tc39.es/ecma262/#sec-proxy-object-internal-methods-and-internal-slots-getownproperty-p
ThrowCompletionOr<Optional<PropertyDescriptor>> ProxyObject::internal_get_own_property(PropertyKey const& property_key) const
{
LIMIT_PROXY_RECURSION_DEPTH();
auto& vm = this->vm();
// 1. Let handler be O.[[ProxyHandler]].
// 2. If handler is null, throw a TypeError exception.
if (m_is_revoked)
return vm.throw_completion<TypeError>(ErrorType::ProxyRevoked);
// 3. Assert: Type(handler) is Object.
// 4. Let target be O.[[ProxyTarget]].
// 5. Let trap be ? GetMethod(handler, "getOwnPropertyDescriptor").
auto trap = TRY(Value(m_handler).get_method(vm, vm.names.getOwnPropertyDescriptor));
// 6. If trap is undefined, then
if (!trap) {
// a. Return ? target.[[GetOwnProperty]](P).
return m_target->internal_get_own_property(property_key);
}
// 7. Let trapResultObj be ? Call(trap, handler, « target, P »).
auto trap_result = TRY(call(vm, *trap, m_handler, m_target, property_key_to_value(vm, property_key)));
// 8. If Type(trapResultObj) is neither Object nor Undefined, throw a TypeError exception.
if (!trap_result.is_object() && !trap_result.is_undefined())
return vm.throw_completion<TypeError>(ErrorType::ProxyGetOwnDescriptorReturn);
// 9. Let targetDesc be ? target.[[GetOwnProperty]](P).
auto target_descriptor = TRY(m_target->internal_get_own_property(property_key));
// 10. If trapResultObj is undefined, then
if (trap_result.is_undefined()) {
// a. If targetDesc is undefined, return undefined.
if (!target_descriptor.has_value())
return Optional<PropertyDescriptor> {};
// b. If targetDesc.[[Configurable]] is false, throw a TypeError exception.
if (!*target_descriptor->configurable)
return vm.throw_completion<TypeError>(ErrorType::ProxyGetOwnDescriptorNonConfigurable);
// c. Let extensibleTarget be ? IsExtensible(target).
auto extensible_target = TRY(m_target->is_extensible());
// d. If extensibleTarget is false, throw a TypeError exception.
if (!extensible_target)
return vm.throw_completion<TypeError>(ErrorType::ProxyGetOwnDescriptorUndefinedReturn);
// e. Return undefined.
return Optional<PropertyDescriptor> {};
}
// 11. Let extensibleTarget be ? IsExtensible(target).
auto extensible_target = TRY(m_target->is_extensible());
// 12. Let resultDesc be ? ToPropertyDescriptor(trapResultObj).
auto result_desc = TRY(to_property_descriptor(vm, trap_result));
// 13. Perform CompletePropertyDescriptor(resultDesc).
result_desc.complete();
// 14. Let valid be IsCompatiblePropertyDescriptor(extensibleTarget, resultDesc, targetDesc).
auto valid = is_compatible_property_descriptor(extensible_target, result_desc, target_descriptor);
// 15. If valid is false, throw a TypeError exception.
if (!valid)
return vm.throw_completion<TypeError>(ErrorType::ProxyGetOwnDescriptorInvalidDescriptor);
// 16. If resultDesc.[[Configurable]] is false, then
if (!*result_desc.configurable) {
// a. If targetDesc is undefined or targetDesc.[[Configurable]] is true, then
if (!target_descriptor.has_value() || *target_descriptor->configurable)
// i. Throw a TypeError exception.
return vm.throw_completion<TypeError>(ErrorType::ProxyGetOwnDescriptorInvalidNonConfig);
// b. If resultDesc has a [[Writable]] field and resultDesc.[[Writable]] is false, then
if (result_desc.writable.has_value() && !*result_desc.writable) {
// i. If targetDesc.[[Writable]] is true, throw a TypeError exception.
if (*target_descriptor->writable)
return vm.throw_completion<TypeError>(ErrorType::ProxyGetOwnDescriptorNonConfigurableNonWritable);
}
}
// 17. Return resultDesc.
return result_desc;
}
// 10.5.6 [[DefineOwnProperty]] ( P, Desc ), https://tc39.es/ecma262/#sec-proxy-object-internal-methods-and-internal-slots-defineownproperty-p-desc
ThrowCompletionOr<bool> ProxyObject::internal_define_own_property(PropertyKey const& property_key, PropertyDescriptor const& property_descriptor, Optional<PropertyDescriptor>*)
{
LIMIT_PROXY_RECURSION_DEPTH();
auto& vm = this->vm();
// 1. Let handler be O.[[ProxyHandler]].
// 2. If handler is null, throw a TypeError exception.
if (m_is_revoked)
return vm.throw_completion<TypeError>(ErrorType::ProxyRevoked);
// 3. Assert: Type(handler) is Object.
// 4. Let target be O.[[ProxyTarget]].
// 5. Let trap be ? GetMethod(handler, "defineProperty").
auto trap = TRY(Value(m_handler).get_method(vm, vm.names.defineProperty));
// 6. If trap is undefined, then
if (!trap) {
// a. Return ? target.[[DefineOwnProperty]](P, Desc).
return m_target->internal_define_own_property(property_key, property_descriptor);
}
// 7. Let descObj be FromPropertyDescriptor(Desc).
auto descriptor_object = from_property_descriptor(vm, property_descriptor);
// 8. Let booleanTrapResult be ToBoolean(? Call(trap, handler, « target, P, descObj »)).
auto trap_result = TRY(call(vm, *trap, m_handler, m_target, property_key_to_value(vm, property_key), descriptor_object)).to_boolean();
// 9. If booleanTrapResult is false, return false.
if (!trap_result)
return false;
// 10. Let targetDesc be ? target.[[GetOwnProperty]](P).
auto target_descriptor = TRY(m_target->internal_get_own_property(property_key));
// 11. Let extensibleTarget be ? IsExtensible(target).
auto extensible_target = TRY(m_target->is_extensible());
// 12. Else, let settingConfigFalse be false.
bool setting_config_false = false;
// 13. If Desc has a [[Configurable]] field and if Desc.[[Configurable]] is false, then
if (property_descriptor.configurable.has_value() && !*property_descriptor.configurable) {
// a. Let settingConfigFalse be true.
setting_config_false = true;
}
// 14. If targetDesc is undefined, then
if (!target_descriptor.has_value()) {
// a. If extensibleTarget is false, throw a TypeError exception.
if (!extensible_target)
return vm.throw_completion<TypeError>(ErrorType::ProxyDefinePropNonExtensible);
// b. If settingConfigFalse is true, throw a TypeError exception.
if (setting_config_false)
return vm.throw_completion<TypeError>(ErrorType::ProxyDefinePropNonConfigurableNonExisting);
}
// 15. Else,
else {
// a. If IsCompatiblePropertyDescriptor(extensibleTarget, Desc, targetDesc) is false, throw a TypeError exception.
if (!is_compatible_property_descriptor(extensible_target, property_descriptor, target_descriptor))
return vm.throw_completion<TypeError>(ErrorType::ProxyDefinePropIncompatibleDescriptor);
// b. If settingConfigFalse is true and targetDesc.[[Configurable]] is true, throw a TypeError exception.
if (setting_config_false && *target_descriptor->configurable)
return vm.throw_completion<TypeError>(ErrorType::ProxyDefinePropExistingConfigurable);
// c. If IsDataDescriptor(targetDesc) is true, targetDesc.[[Configurable]] is false, and targetDesc.[[Writable]] is true, then
if (target_descriptor->is_data_descriptor() && !*target_descriptor->configurable && *target_descriptor->writable) {
// i. If Desc has a [[Writable]] field and Desc.[[Writable]] is false, throw a TypeError exception.
if (property_descriptor.writable.has_value() && !*property_descriptor.writable)
return vm.throw_completion<TypeError>(ErrorType::ProxyDefinePropNonWritable);
}
}
// 16. Return true.
return true;
}
// 10.5.7 [[HasProperty]] ( P ), https://tc39.es/ecma262/#sec-proxy-object-internal-methods-and-internal-slots-hasproperty-p
ThrowCompletionOr<bool> ProxyObject::internal_has_property(PropertyKey const& property_key) const
{
LIMIT_PROXY_RECURSION_DEPTH();
auto& vm = this->vm();
// 1. Let handler be O.[[ProxyHandler]].
// 2. If handler is null, throw a TypeError exception.
if (m_is_revoked)
return vm.throw_completion<TypeError>(ErrorType::ProxyRevoked);
// 3. Assert: Type(handler) is Object.
// 4. Let target be O.[[ProxyTarget]].
// NOTE: We need to protect ourselves from a Proxy with the handler's prototype set to the
// Proxy itself, which would by default bounce between these functions indefinitely and lead to
// a stack overflow when the Proxy's (p) or Proxy handler's (h) Object::get() is called and the
// handler doesn't have a `has` trap:
//
// 1. p -> ProxyObject::internal_has_property() <- you are here
// 2. target -> Object::internal_has_property()
// 3. target.[[Prototype]] (which is internal_has_property) -> Object::internal_has_property()
//
// In JS code: `const proxy = new Proxy({}, {}); proxy.__proto__ = Object.create(proxy); "foo" in proxy;`
if (vm.did_reach_stack_space_limit())
return vm.throw_completion<InternalError>(ErrorType::CallStackSizeExceeded);
// 5. Let trap be ? GetMethod(handler, "has").
auto trap = TRY(Value(m_handler).get_method(vm, vm.names.has));
// 6. If trap is undefined, then
if (!trap) {
// a. Return ? target.[[HasProperty]](P).
return m_target->internal_has_property(property_key);
}
// 7. Let booleanTrapResult be ToBoolean(? Call(trap, handler, « target, P »)).
auto trap_result = TRY(call(vm, *trap, m_handler, m_target, property_key_to_value(vm, property_key))).to_boolean();
// 8. If booleanTrapResult is false, then
if (!trap_result) {
// a. Let targetDesc be ? target.[[GetOwnProperty]](P).
auto target_descriptor = TRY(m_target->internal_get_own_property(property_key));
// b. If targetDesc is not undefined, then
if (target_descriptor.has_value()) {
// i. If targetDesc.[[Configurable]] is false, throw a TypeError exception.
if (!*target_descriptor->configurable)
return vm.throw_completion<TypeError>(ErrorType::ProxyHasExistingNonConfigurable);
// ii. Let extensibleTarget be ? IsExtensible(target).
auto extensible_target = TRY(m_target->is_extensible());
// iii. If extensibleTarget is false, throw a TypeError exception.
if (!extensible_target)
return vm.throw_completion<TypeError>(ErrorType::ProxyHasExistingNonExtensible);
}
}
// 9. Return booleanTrapResult.
return trap_result;
}
// 10.5.8 [[Get]] ( P, Receiver ), https://tc39.es/ecma262/#sec-proxy-object-internal-methods-and-internal-slots-get-p-receiver
ThrowCompletionOr<Value> ProxyObject::internal_get(PropertyKey const& property_key, Value receiver, CacheablePropertyMetadata*, PropertyLookupPhase) const
{
LIMIT_PROXY_RECURSION_DEPTH();
// NOTE: We don't return any cacheable metadata for proxy lookups.
VERIFY(!receiver.is_empty());
auto& vm = this->vm();
VERIFY(!receiver.is_empty());
// 1. Let handler be O.[[ProxyHandler]].
// 2. If handler is null, throw a TypeError exception.
if (m_is_revoked)
return vm.throw_completion<TypeError>(ErrorType::ProxyRevoked);
// 3. Assert: Type(handler) is Object.
// 4. Let target be O.[[ProxyTarget]].
// NOTE: We need to protect ourselves from a Proxy with its (or handler's) prototype set to the
// Proxy itself, which would by default bounce between these functions indefinitely and lead to
// a stack overflow when the Proxy's (p) or Proxy handler's (h) Object::get() is called and the
// handler doesn't have a `get` trap:
//
// 1. p -> ProxyObject::internal_get() <- you are here
// 2. h -> Value::get_method()
// 3. h -> Value::get()
// 4. h -> Object::internal_get()
// 5. h -> Object::internal_get_prototype_of() (result is p)
// 6. goto 1
//
// In JS code: `h = {}; p = new Proxy({}, h); h.__proto__ = p; p.foo // or h.foo`
if (vm.did_reach_stack_space_limit())
return vm.throw_completion<InternalError>(ErrorType::CallStackSizeExceeded);
// 5. Let trap be ? GetMethod(handler, "get").
auto trap = TRY(Value(m_handler).get_method(vm, vm.names.get));
// 6. If trap is undefined, then
if (!trap) {
// a. Return ? target.[[Get]](P, Receiver).
return m_target->internal_get(property_key, receiver);
}
// 7. Let trapResult be ? Call(trap, handler, « target, P, Receiver »).
auto trap_result = TRY(call(vm, *trap, m_handler, m_target, property_key_to_value(vm, property_key), receiver));
// 8. Let targetDesc be ? target.[[GetOwnProperty]](P).
auto target_descriptor = TRY(m_target->internal_get_own_property(property_key));
// 9. If targetDesc is not undefined and targetDesc.[[Configurable]] is false, then
if (target_descriptor.has_value() && !*target_descriptor->configurable) {
// a. If IsDataDescriptor(targetDesc) is true and targetDesc.[[Writable]] is false, then
if (target_descriptor->is_data_descriptor() && !*target_descriptor->writable) {
// i. If SameValue(trapResult, targetDesc.[[Value]]) is false, throw a TypeError exception.
if (!same_value(trap_result, *target_descriptor->value))
return vm.throw_completion<TypeError>(ErrorType::ProxyGetImmutableDataProperty);
}
// b. If IsAccessorDescriptor(targetDesc) is true and targetDesc.[[Get]] is undefined, then
if (target_descriptor->is_accessor_descriptor() && !*target_descriptor->get) {
// i. If trapResult is not undefined, throw a TypeError exception.
if (!trap_result.is_undefined())
return vm.throw_completion<TypeError>(ErrorType::ProxyGetNonConfigurableAccessor);
}
}
// 10. Return trapResult.
return trap_result;
}
// 10.5.9 [[Set]] ( P, V, Receiver ), https://tc39.es/ecma262/#sec-proxy-object-internal-methods-and-internal-slots-set-p-v-receiver
ThrowCompletionOr<bool> ProxyObject::internal_set(PropertyKey const& property_key, Value value, Value receiver, CacheablePropertyMetadata*)
{
LIMIT_PROXY_RECURSION_DEPTH();
auto& vm = this->vm();
VERIFY(!value.is_empty());
VERIFY(!receiver.is_empty());
// 1. Let handler be O.[[ProxyHandler]].
// 2. If handler is null, throw a TypeError exception.
if (m_is_revoked)
return vm.throw_completion<TypeError>(ErrorType::ProxyRevoked);
// 3. Assert: Type(handler) is Object.
// 4. Let target be O.[[ProxyTarget]].
// NOTE: We need to protect ourselves from a Proxy with its prototype set to the
// Proxy itself, which would by default bounce between these functions indefinitely and lead to
// a stack overflow when the Proxy's (p) or Proxy handler's (h) Object::get() is called and the
// handler doesn't have a `has` trap:
//
// 1. p -> ProxyObject::internal_set() <- you are here
// 2. target -> Object::internal_set()
// 3. target -> Object::ordinary_set_with_own_descriptor()
// 4. target.[[Prototype]] -> Object::internal_set()
// 5. target.[[Prototype]] -> Object::ordinary_set_with_own_descriptor()
// 6. target.[[Prototype]].[[Prototype]] (which is ProxyObject) -> Object::internal_set()
//
// In JS code: `const proxy = new Proxy({}, {}); proxy.__proto__ = Object.create(proxy); proxy["foo"] = "bar";`
if (vm.did_reach_stack_space_limit())
return vm.throw_completion<InternalError>(ErrorType::CallStackSizeExceeded);
// 5. Let trap be ? GetMethod(handler, "set").
auto trap = TRY(Value(m_handler).get_method(vm, vm.names.set));
// 6. If trap is undefined, then
if (!trap) {
// a. Return ? target.[[Set]](P, V, Receiver).
return m_target->internal_set(property_key, value, receiver);
}
// 7. Let booleanTrapResult be ToBoolean(? Call(trap, handler, « target, P, V, Receiver »)).
auto trap_result = TRY(call(vm, *trap, m_handler, m_target, property_key_to_value(vm, property_key), value, receiver)).to_boolean();
// 8. If booleanTrapResult is false, return false.
if (!trap_result)
return false;
// 9. Let targetDesc be ? target.[[GetOwnProperty]](P).
auto target_descriptor = TRY(m_target->internal_get_own_property(property_key));
// 10. If targetDesc is not undefined and targetDesc.[[Configurable]] is false, then
if (target_descriptor.has_value() && !*target_descriptor->configurable) {
// a. If IsDataDescriptor(targetDesc) is true and targetDesc.[[Writable]] is false, then
if (target_descriptor->is_data_descriptor() && !*target_descriptor->writable) {
// i. If SameValue(V, targetDesc.[[Value]]) is false, throw a TypeError exception.
if (!same_value(value, *target_descriptor->value))
return vm.throw_completion<TypeError>(ErrorType::ProxySetImmutableDataProperty);
}
// b. If IsAccessorDescriptor(targetDesc) is true, then
if (target_descriptor->is_accessor_descriptor()) {
// i. If targetDesc.[[Set]] is undefined, throw a TypeError exception.
if (!*target_descriptor->set)
return vm.throw_completion<TypeError>(ErrorType::ProxySetNonConfigurableAccessor);
}
}
// 11. Return true.
return true;
}
// 10.5.10 [[Delete]] ( P ), https://tc39.es/ecma262/#sec-proxy-object-internal-methods-and-internal-slots-delete-p
ThrowCompletionOr<bool> ProxyObject::internal_delete(PropertyKey const& property_key)
{
LIMIT_PROXY_RECURSION_DEPTH();
auto& vm = this->vm();
// 1. Let handler be O.[[ProxyHandler]].
// 2. If handler is null, throw a TypeError exception.
if (m_is_revoked)
return vm.throw_completion<TypeError>(ErrorType::ProxyRevoked);
// 3. Assert: Type(handler) is Object.
// 4. Let target be O.[[ProxyTarget]].
// 5. Let trap be ? GetMethod(handler, "deleteProperty").
auto trap = TRY(Value(m_handler).get_method(vm, vm.names.deleteProperty));
// 6. If trap is undefined, then
if (!trap) {
// a. Return ? target.[[Delete]](P).
return m_target->internal_delete(property_key);
}
// 7. Let booleanTrapResult be ToBoolean(? Call(trap, handler, « target, P »)).
auto trap_result = TRY(call(vm, *trap, m_handler, m_target, property_key_to_value(vm, property_key))).to_boolean();
// 8. If booleanTrapResult is false, return false.
if (!trap_result)
return false;
// 9. Let targetDesc be ? target.[[GetOwnProperty]](P).
auto target_descriptor = TRY(m_target->internal_get_own_property(property_key));
// 10. If targetDesc is undefined, return true.
if (!target_descriptor.has_value())
return true;
// 11. If targetDesc.[[Configurable]] is false, throw a TypeError exception.
if (!*target_descriptor->configurable)
return vm.throw_completion<TypeError>(ErrorType::ProxyDeleteNonConfigurable);
// 12. Let extensibleTarget be ? IsExtensible(target).
auto extensible_target = TRY(m_target->is_extensible());
// 13. If extensibleTarget is false, throw a TypeError exception.
if (!extensible_target)
return vm.throw_completion<TypeError>(ErrorType::ProxyDeleteNonExtensible);
// 14. Return true.
return true;
}
// 10.5.11 [[OwnPropertyKeys]] ( ), https://tc39.es/ecma262/#sec-proxy-object-internal-methods-and-internal-slots-ownpropertykeys
ThrowCompletionOr<GC::MarkedVector<Value>> ProxyObject::internal_own_property_keys() const
{
LIMIT_PROXY_RECURSION_DEPTH();
auto& vm = this->vm();
// 1. Let handler be O.[[ProxyHandler]].
// 2. If handler is null, throw a TypeError exception.
if (m_is_revoked)
return vm.throw_completion<TypeError>(ErrorType::ProxyRevoked);
// 3. Assert: Type(handler) is Object.
// 4. Let target be O.[[ProxyTarget]].
// 5. Let trap be ? GetMethod(handler, "ownKeys").
auto trap = TRY(Value(m_handler).get_method(vm, vm.names.ownKeys));
// 6. If trap is undefined, then
if (!trap) {
// a. Return ? target.[[OwnPropertyKeys]]().
return m_target->internal_own_property_keys();
}
// 7. Let trapResultArray be ? Call(trap, handler, « target »).
auto trap_result_array = TRY(call(vm, *trap, m_handler, m_target));
// 8. Let trapResult be ? CreateListFromArrayLike(trapResultArray, « String, Symbol »).
HashTable<PropertyKey> unique_keys;
auto trap_result = TRY(create_list_from_array_like(vm, trap_result_array, [&](auto value) -> ThrowCompletionOr<void> {
if (!value.is_string() && !value.is_symbol())
return vm.throw_completion<TypeError>(ErrorType::ProxyOwnPropertyKeysNotStringOrSymbol);
auto property_key = MUST(value.to_property_key(vm));
unique_keys.set(property_key, AK::HashSetExistingEntryBehavior::Keep);
return {};
}));
// 9. If trapResult contains any duplicate entries, throw a TypeError exception.
if (unique_keys.size() != trap_result.size())
return vm.throw_completion<TypeError>(ErrorType::ProxyOwnPropertyKeysDuplicates);
// 10. Let extensibleTarget be ? IsExtensible(target).
auto extensible_target = TRY(m_target->is_extensible());
// 11. Let targetKeys be ? target.[[OwnPropertyKeys]]().
auto target_keys = TRY(m_target->internal_own_property_keys());
// 12. Assert: targetKeys is a List of property keys.
// 13. Assert: targetKeys contains no duplicate entries.
// 14. Let targetConfigurableKeys be a new empty List.
auto target_configurable_keys = GC::MarkedVector<Value> { heap() };
// 15. Let targetNonconfigurableKeys be a new empty List.
auto target_nonconfigurable_keys = GC::MarkedVector<Value> { heap() };
// 16. For each element key of targetKeys, do
for (auto& key : target_keys) {
auto property_key = MUST(PropertyKey::from_value(vm, key));
// a. Let desc be ? target.[[GetOwnProperty]](key).
auto descriptor = TRY(m_target->internal_get_own_property(property_key));
// b. If desc is not undefined and desc.[[Configurable]] is false, then
if (descriptor.has_value() && !*descriptor->configurable) {
// i. Append key as an element of targetNonconfigurableKeys.
target_nonconfigurable_keys.append(key);
}
// c. Else,
else {
// i. Append key as an element of targetConfigurableKeys.
target_configurable_keys.append(key);
}
}
// 17. If extensibleTarget is true and targetNonconfigurableKeys is empty, then
if (extensible_target && target_nonconfigurable_keys.is_empty()) {
// a. Return trapResult.
return { move(trap_result) };
}
// 18. Let uncheckedResultKeys be a List whose elements are the elements of trapResult.
auto unchecked_result_keys = GC::MarkedVector<Value> { heap() };
unchecked_result_keys.extend(trap_result);
// 19. For each element key of targetNonconfigurableKeys, do
for (auto& key : target_nonconfigurable_keys) {
// a. If key is not an element of uncheckedResultKeys, throw a TypeError exception.
if (!unchecked_result_keys.contains_slow(key))
return vm.throw_completion<TypeError>(ErrorType::ProxyOwnPropertyKeysSkippedNonconfigurableProperty, key.to_string_without_side_effects());
// b. Remove key from uncheckedResultKeys.
unchecked_result_keys.remove_first_matching([&](auto& value) {
return same_value(value, key);
});
}
// 20. If extensibleTarget is true, return trapResult.
if (extensible_target)
return { move(trap_result) };
// 21. For each element key of targetConfigurableKeys, do
for (auto& key : target_configurable_keys) {
// a. If key is not an element of uncheckedResultKeys, throw a TypeError exception.
if (!unchecked_result_keys.contains_slow(key))
return vm.throw_completion<TypeError>(ErrorType::ProxyOwnPropertyKeysNonExtensibleSkippedProperty, key.to_string_without_side_effects());
// b. Remove key from uncheckedResultKeys.
unchecked_result_keys.remove_first_matching([&](auto& value) {
return same_value(value, key);
});
}
// 22. If uncheckedResultKeys is not empty, throw a TypeError exception.
if (!unchecked_result_keys.is_empty())
return vm.throw_completion<TypeError>(ErrorType::ProxyOwnPropertyKeysNonExtensibleNewProperty, unchecked_result_keys[0].to_string_without_side_effects());
// 23. Return trapResult.
return { move(trap_result) };
}
// 10.5.12 [[Call]] ( thisArgument, argumentsList ), https://tc39.es/ecma262/#sec-proxy-object-internal-methods-and-internal-slots-call-thisargument-argumentslist
ThrowCompletionOr<Value> ProxyObject::internal_call(Value this_argument, ReadonlySpan<Value> arguments_list)
{
LIMIT_PROXY_RECURSION_DEPTH();
auto& vm = this->vm();
auto& realm = *vm.current_realm();
// A Proxy exotic object only has a [[Call]] internal method if the initial value of its [[ProxyTarget]] internal slot is an object that has a [[Call]] internal method.
VERIFY(is_function());
// 1. Let handler be O.[[ProxyHandler]].
// 2. If handler is null, throw a TypeError exception.
if (m_is_revoked)
return vm.throw_completion<TypeError>(ErrorType::ProxyRevoked);
// 3. Assert: Type(handler) is Object.
// 4. Let target be O.[[ProxyTarget]].
// 5. Let trap be ? GetMethod(handler, "apply").
auto trap = TRY(Value(m_handler).get_method(vm, vm.names.apply));
// 6. If trap is undefined, then
if (!trap) {
// a. Return ? Call(target, thisArgument, argumentsList).
return call(vm, m_target, this_argument, arguments_list);
}
// 7. Let argArray be CreateArrayFromList(argumentsList).
auto arguments_array = Array::create_from(realm, arguments_list);
// 8. Return ? Call(trap, handler, « target, thisArgument, argArray »).
return call(vm, trap, m_handler, m_target, this_argument, arguments_array);
}
bool ProxyObject::has_constructor() const
{
// Note: A Proxy exotic object only has a [[Construct]] internal method if the initial value of
// its [[ProxyTarget]] internal slot is an object that has a [[Construct]] internal method.
if (!is_function())
return false;
return static_cast<FunctionObject&>(*m_target).has_constructor();
}
// 10.5.13 [[Construct]] ( argumentsList, newTarget ), https://tc39.es/ecma262/#sec-proxy-object-internal-methods-and-internal-slots-construct-argumentslist-newtarget
ThrowCompletionOr<GC::Ref<Object>> ProxyObject::internal_construct(ReadonlySpan<Value> arguments_list, FunctionObject& new_target)
{
LIMIT_PROXY_RECURSION_DEPTH();
auto& vm = this->vm();
auto& realm = *vm.current_realm();
// A Proxy exotic object only has a [[Construct]] internal method if the initial value of its [[ProxyTarget]] internal slot is an object that has a [[Construct]] internal method.
VERIFY(is_function());
// 1. Let handler be O.[[ProxyHandler]].
// 2. If handler is null, throw a TypeError exception.
if (m_is_revoked)
return vm.throw_completion<TypeError>(ErrorType::ProxyRevoked);
// 3. Assert: Type(handler) is Object.
// 4. Let target be O.[[ProxyTarget]].
// 5. Assert: IsConstructor(target) is true.
// 6. Let trap be ? GetMethod(handler, "construct").
auto trap = TRY(Value(m_handler).get_method(vm, vm.names.construct));
// 7. If trap is undefined, then
if (!trap) {
// a. Return ? Construct(target, argumentsList, newTarget).
return construct(vm, static_cast<FunctionObject&>(*m_target), arguments_list, &new_target);
}
// 8. Let argArray be CreateArrayFromList(argumentsList).
auto arguments_array = Array::create_from(realm, arguments_list);
// 9. Let newObj be ? Call(trap, handler, « target, argArray, newTarget »).
auto new_object = TRY(call(vm, trap, m_handler, m_target, arguments_array, &new_target));
// 10. If Type(newObj) is not Object, throw a TypeError exception.
if (!new_object.is_object())
return vm.throw_completion<TypeError>(ErrorType::ProxyConstructBadReturnType);
// 11. Return newObj.
return new_object.as_object();
}
void ProxyObject::visit_edges(Cell::Visitor& visitor)
{
Base::visit_edges(visitor);
visitor.visit(m_target);
visitor.visit(m_handler);
}
DeprecatedFlyString const& ProxyObject::name() const
{
VERIFY(is_function());
return static_cast<FunctionObject&>(*m_target).name();
}
}