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ladybird/Userland/Libraries/LibJS/Runtime/JSONObject.cpp
Andreas Kling 3c74dc9f4d LibJS: Segregate GC-allocated objects by type 
This patch adds two macros to declare per-type allocators:

- JS_DECLARE_ALLOCATOR(TypeName)
- JS_DEFINE_ALLOCATOR(TypeName)

When used, they add a type-specific CellAllocator that the Heap will
delegate allocation requests to.

The result of this is that GC objects of the same type always end up
within the same HeapBlock, drastically reducing the ability to perform
type confusion attacks.

It also improves HeapBlock utilization, since each block now has cells
sized exactly to the type used within that block. (Previously we only
had a handful of block sizes available, and most GC allocations ended
up with a large amount of slack in their tails.)

There is a small performance hit from this, but I'm sure we can make
up for it elsewhere.

Note that the old size-based allocators still exist, and we fall back
to them for any type that doesn't have its own CellAllocator.
2023-11-19 12:10:31 +01:00

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/*
* Copyright (c) 2020, Matthew Olsson <mattco@serenityos.org>
*
* SPDX-License-Identifier: BSD-2-Clause
*/
#include <AK/Function.h>
#include <AK/JsonArray.h>
#include <AK/JsonObject.h>
#include <AK/JsonParser.h>
#include <AK/StringBuilder.h>
#include <AK/TypeCasts.h>
#include <AK/Utf16View.h>
#include <AK/Utf8View.h>
#include <LibJS/Runtime/AbstractOperations.h>
#include <LibJS/Runtime/Array.h>
#include <LibJS/Runtime/BigIntObject.h>
#include <LibJS/Runtime/BooleanObject.h>
#include <LibJS/Runtime/Error.h>
#include <LibJS/Runtime/FunctionObject.h>
#include <LibJS/Runtime/GlobalObject.h>
#include <LibJS/Runtime/JSONObject.h>
#include <LibJS/Runtime/NumberObject.h>
#include <LibJS/Runtime/Object.h>
#include <LibJS/Runtime/StringObject.h>
#include <LibJS/Runtime/ValueInlines.h>
namespace JS {
JS_DEFINE_ALLOCATOR(JSONObject);
JSONObject::JSONObject(Realm& realm)
: Object(ConstructWithPrototypeTag::Tag, realm.intrinsics().object_prototype())
{
}
void JSONObject::initialize(Realm& realm)
{
auto& vm = this->vm();
Base::initialize(realm);
u8 attr = Attribute::Writable | Attribute::Configurable;
define_native_function(realm, vm.names.stringify, stringify, 3, attr);
define_native_function(realm, vm.names.parse, parse, 2, attr);
// 25.5.3 JSON [ @@toStringTag ], https://tc39.es/ecma262/#sec-json-@@tostringtag
define_direct_property(vm.well_known_symbol_to_string_tag(), PrimitiveString::create(vm, "JSON"_string), Attribute::Configurable);
}
// 25.5.2 JSON.stringify ( value [ , replacer [ , space ] ] ), https://tc39.es/ecma262/#sec-json.stringify
ThrowCompletionOr<Optional<DeprecatedString>> JSONObject::stringify_impl(VM& vm, Value value, Value replacer, Value space)
{
auto& realm = *vm.current_realm();
StringifyState state;
if (replacer.is_object()) {
if (replacer.as_object().is_function()) {
state.replacer_function = &replacer.as_function();
} else {
auto is_array = TRY(replacer.is_array(vm));
if (is_array) {
auto& replacer_object = replacer.as_object();
auto replacer_length = TRY(length_of_array_like(vm, replacer_object));
Vector<DeprecatedString> list;
for (size_t i = 0; i < replacer_length; ++i) {
auto replacer_value = TRY(replacer_object.get(i));
Optional<DeprecatedString> item;
if (replacer_value.is_string()) {
item = replacer_value.as_string().deprecated_string();
} else if (replacer_value.is_number()) {
item = MUST(replacer_value.to_deprecated_string(vm));
} else if (replacer_value.is_object()) {
auto& value_object = replacer_value.as_object();
if (is<StringObject>(value_object) || is<NumberObject>(value_object))
item = TRY(replacer_value.to_deprecated_string(vm));
}
if (item.has_value() && !list.contains_slow(*item)) {
list.append(*item);
}
}
state.property_list = list;
}
}
}
if (space.is_object()) {
auto& space_object = space.as_object();
if (is<NumberObject>(space_object))
space = TRY(space.to_number(vm));
else if (is<StringObject>(space_object))
space = TRY(space.to_primitive_string(vm));
}
if (space.is_number()) {
auto space_mv = MUST(space.to_integer_or_infinity(vm));
space_mv = min(10, space_mv);
state.gap = space_mv < 1 ? DeprecatedString::empty() : DeprecatedString::repeated(' ', space_mv);
} else if (space.is_string()) {
auto string = space.as_string().deprecated_string();
if (string.length() <= 10)
state.gap = string;
else
state.gap = string.substring(0, 10);
} else {
state.gap = DeprecatedString::empty();
}
auto wrapper = Object::create(realm, realm.intrinsics().object_prototype());
MUST(wrapper->create_data_property_or_throw(DeprecatedString::empty(), value));
return serialize_json_property(vm, state, DeprecatedString::empty(), wrapper);
}
// 25.5.2 JSON.stringify ( value [ , replacer [ , space ] ] ), https://tc39.es/ecma262/#sec-json.stringify
JS_DEFINE_NATIVE_FUNCTION(JSONObject::stringify)
{
if (!vm.argument_count())
return js_undefined();
auto value = vm.argument(0);
auto replacer = vm.argument(1);
auto space = vm.argument(2);
auto maybe_string = TRY(stringify_impl(vm, value, replacer, space));
if (!maybe_string.has_value())
return js_undefined();
return PrimitiveString::create(vm, maybe_string.release_value());
}
// 25.5.2.1 SerializeJSONProperty ( state, key, holder ), https://tc39.es/ecma262/#sec-serializejsonproperty
ThrowCompletionOr<Optional<DeprecatedString>> JSONObject::serialize_json_property(VM& vm, StringifyState& state, PropertyKey const& key, Object* holder)
{
// 1. Let value be ? Get(holder, key).
auto value = TRY(holder->get(key));
// 2. If Type(value) is Object or BigInt, then
if (value.is_object() || value.is_bigint()) {
// a. Let toJSON be ? GetV(value, "toJSON").
auto to_json = TRY(value.get(vm, vm.names.toJSON));
// b. If IsCallable(toJSON) is true, then
if (to_json.is_function()) {
// i. Set value to ? Call(toJSON, value, « key »).
value = TRY(call(vm, to_json.as_function(), value, PrimitiveString::create(vm, key.to_string())));
}
}
// 3. If state.[[ReplacerFunction]] is not undefined, then
if (state.replacer_function) {
// a. Set value to ? Call(state.[[ReplacerFunction]], holder, « key, value »).
value = TRY(call(vm, *state.replacer_function, holder, PrimitiveString::create(vm, key.to_string()), value));
}
// 4. If Type(value) is Object, then
if (value.is_object()) {
auto& value_object = value.as_object();
// a. If value has a [[NumberData]] internal slot, then
if (is<NumberObject>(value_object)) {
// i. Set value to ? ToNumber(value).
value = TRY(value.to_number(vm));
}
// b. Else if value has a [[StringData]] internal slot, then
else if (is<StringObject>(value_object)) {
// i. Set value to ? ToString(value).
value = TRY(value.to_primitive_string(vm));
}
// c. Else if value has a [[BooleanData]] internal slot, then
else if (is<BooleanObject>(value_object)) {
// i. Set value to value.[[BooleanData]].
value = Value(static_cast<BooleanObject&>(value_object).boolean());
}
// d. Else if value has a [[BigIntData]] internal slot, then
else if (is<BigIntObject>(value_object)) {
// i. Set value to value.[[BigIntData]].
value = Value(&static_cast<BigIntObject&>(value_object).bigint());
}
}
// 5. If value is null, return "null".
if (value.is_null())
return "null"sv;
// 6. If value is true, return "true".
// 7. If value is false, return "false".
if (value.is_boolean())
return value.as_bool() ? "true"sv : "false"sv;
// 8. If Type(value) is String, return QuoteJSONString(value).
if (value.is_string())
return quote_json_string(value.as_string().deprecated_string());
// 9. If Type(value) is Number, then
if (value.is_number()) {
// a. If value is finite, return ! ToString(value).
if (value.is_finite_number())
return MUST(value.to_deprecated_string(vm));
// b. Return "null".
return "null"sv;
}
// 10. If Type(value) is BigInt, throw a TypeError exception.
if (value.is_bigint())
return vm.throw_completion<TypeError>(ErrorType::JsonBigInt);
// 11. If Type(value) is Object and IsCallable(value) is false, then
if (value.is_object() && !value.is_function()) {
// a. Let isArray be ? IsArray(value).
auto is_array = TRY(value.is_array(vm));
// b. If isArray is true, return ? SerializeJSONArray(state, value).
if (is_array)
return TRY(serialize_json_array(vm, state, value.as_object()));
// c. Return ? SerializeJSONObject(state, value).
return TRY(serialize_json_object(vm, state, value.as_object()));
}
// 12. Return undefined.
return Optional<DeprecatedString> {};
}
// 25.5.2.4 SerializeJSONObject ( state, value ), https://tc39.es/ecma262/#sec-serializejsonobject
ThrowCompletionOr<DeprecatedString> JSONObject::serialize_json_object(VM& vm, StringifyState& state, Object& object)
{
if (state.seen_objects.contains(&object))
return vm.throw_completion<TypeError>(ErrorType::JsonCircular);
state.seen_objects.set(&object);
DeprecatedString previous_indent = state.indent;
state.indent = DeprecatedString::formatted("{}{}", state.indent, state.gap);
Vector<DeprecatedString> property_strings;
auto process_property = [&](PropertyKey const& key) -> ThrowCompletionOr<void> {
if (key.is_symbol())
return {};
auto serialized_property_string = TRY(serialize_json_property(vm, state, key, &object));
if (serialized_property_string.has_value()) {
property_strings.append(DeprecatedString::formatted(
"{}:{}{}",
quote_json_string(key.to_string()),
state.gap.is_empty() ? "" : " ",
serialized_property_string));
}
return {};
};
if (state.property_list.has_value()) {
auto property_list = state.property_list.value();
for (auto& property : property_list)
TRY(process_property(property));
} else {
auto property_list = TRY(object.enumerable_own_property_names(PropertyKind::Key));
for (auto& property : property_list)
TRY(process_property(property.as_string().deprecated_string()));
}
StringBuilder builder;
if (property_strings.is_empty()) {
builder.append("{}"sv);
} else {
bool first = true;
builder.append('{');
if (state.gap.is_empty()) {
for (auto& property_string : property_strings) {
if (!first)
builder.append(',');
first = false;
builder.append(property_string);
}
} else {
builder.append('\n');
builder.append(state.indent);
auto separator = DeprecatedString::formatted(",\n{}", state.indent);
for (auto& property_string : property_strings) {
if (!first)
builder.append(separator);
first = false;
builder.append(property_string);
}
builder.append('\n');
builder.append(previous_indent);
}
builder.append('}');
}
state.seen_objects.remove(&object);
state.indent = previous_indent;
return builder.to_deprecated_string();
}
// 25.5.2.5 SerializeJSONArray ( state, value ), https://tc39.es/ecma262/#sec-serializejsonarray
ThrowCompletionOr<DeprecatedString> JSONObject::serialize_json_array(VM& vm, StringifyState& state, Object& object)
{
if (state.seen_objects.contains(&object))
return vm.throw_completion<TypeError>(ErrorType::JsonCircular);
state.seen_objects.set(&object);
DeprecatedString previous_indent = state.indent;
state.indent = DeprecatedString::formatted("{}{}", state.indent, state.gap);
Vector<DeprecatedString> property_strings;
auto length = TRY(length_of_array_like(vm, object));
// Optimization
property_strings.ensure_capacity(length);
for (size_t i = 0; i < length; ++i) {
auto serialized_property_string = TRY(serialize_json_property(vm, state, i, &object));
if (!serialized_property_string.has_value()) {
property_strings.append("null"sv);
} else {
property_strings.append(serialized_property_string.release_value());
}
}
StringBuilder builder;
if (property_strings.is_empty()) {
builder.append("[]"sv);
} else {
if (state.gap.is_empty()) {
builder.append('[');
bool first = true;
for (auto& property_string : property_strings) {
if (!first)
builder.append(',');
first = false;
builder.append(property_string);
}
builder.append(']');
} else {
builder.append("[\n"sv);
builder.append(state.indent);
auto separator = DeprecatedString::formatted(",\n{}", state.indent);
bool first = true;
for (auto& property_string : property_strings) {
if (!first)
builder.append(separator);
first = false;
builder.append(property_string);
}
builder.append('\n');
builder.append(previous_indent);
builder.append(']');
}
}
state.seen_objects.remove(&object);
state.indent = previous_indent;
return builder.to_deprecated_string();
}
// 25.5.2.2 QuoteJSONString ( value ), https://tc39.es/ecma262/#sec-quotejsonstring
DeprecatedString JSONObject::quote_json_string(DeprecatedString string)
{
// 1. Let product be the String value consisting solely of the code unit 0x0022 (QUOTATION MARK).
StringBuilder builder;
builder.append('"');
// 2. For each code point C of StringToCodePoints(value), do
auto utf_view = Utf8View(string);
for (auto code_point : utf_view) {
// a. If C is listed in the “Code Point” column of Table 70, then
// i. Set product to the string-concatenation of product and the escape sequence for C as specified in the “Escape Sequence” column of the corresponding row.
switch (code_point) {
case '\b':
builder.append("\\b"sv);
break;
case '\t':
builder.append("\\t"sv);
break;
case '\n':
builder.append("\\n"sv);
break;
case '\f':
builder.append("\\f"sv);
break;
case '\r':
builder.append("\\r"sv);
break;
case '"':
builder.append("\\\""sv);
break;
case '\\':
builder.append("\\\\"sv);
break;
default:
// b. Else if C has a numeric value less than 0x0020 (SPACE), or if C has the same numeric value as a leading surrogate or trailing surrogate, then
if (code_point < 0x20 || is_unicode_surrogate(code_point)) {
// i. Let unit be the code unit whose numeric value is that of C.
// ii. Set product to the string-concatenation of product and UnicodeEscape(unit).
builder.appendff("\\u{:04x}", code_point);
}
// c. Else,
else {
// i. Set product to the string-concatenation of product and UTF16EncodeCodePoint(C).
builder.append_code_point(code_point);
}
}
}
// 3. Set product to the string-concatenation of product and the code unit 0x0022 (QUOTATION MARK).
builder.append('"');
// 4. Return product.
return builder.to_deprecated_string();
}
// 25.5.1 JSON.parse ( text [ , reviver ] ), https://tc39.es/ecma262/#sec-json.parse
JS_DEFINE_NATIVE_FUNCTION(JSONObject::parse)
{
auto& realm = *vm.current_realm();
auto string = TRY(vm.argument(0).to_deprecated_string(vm));
auto reviver = vm.argument(1);
auto json = JsonValue::from_string(string);
if (json.is_error())
return vm.throw_completion<SyntaxError>(ErrorType::JsonMalformed);
Value unfiltered = parse_json_value(vm, json.value());
if (reviver.is_function()) {
auto root = Object::create(realm, realm.intrinsics().object_prototype());
auto root_name = DeprecatedString::empty();
MUST(root->create_data_property_or_throw(root_name, unfiltered));
return internalize_json_property(vm, root, root_name, reviver.as_function());
}
return unfiltered;
}
Value JSONObject::parse_json_value(VM& vm, JsonValue const& value)
{
if (value.is_object())
return Value(parse_json_object(vm, value.as_object()));
if (value.is_array())
return Value(parse_json_array(vm, value.as_array()));
if (value.is_null())
return js_null();
if (value.is_i32())
return Value(value.as_i32());
if (value.is_number())
return Value(value.to_double(0));
if (value.is_string())
return PrimitiveString::create(vm, value.to_deprecated_string());
if (value.is_bool())
return Value(static_cast<bool>(value.as_bool()));
VERIFY_NOT_REACHED();
}
Object* JSONObject::parse_json_object(VM& vm, JsonObject const& json_object)
{
auto& realm = *vm.current_realm();
auto object = Object::create(realm, realm.intrinsics().object_prototype());
json_object.for_each_member([&](auto& key, auto& value) {
object->define_direct_property(key, parse_json_value(vm, value), default_attributes);
});
return object;
}
Array* JSONObject::parse_json_array(VM& vm, JsonArray const& json_array)
{
auto& realm = *vm.current_realm();
auto array = MUST(Array::create(realm, 0));
size_t index = 0;
json_array.for_each([&](auto& value) {
array->define_direct_property(index++, parse_json_value(vm, value), default_attributes);
});
return array;
}
// 25.5.1.1 InternalizeJSONProperty ( holder, name, reviver ), https://tc39.es/ecma262/#sec-internalizejsonproperty
ThrowCompletionOr<Value> JSONObject::internalize_json_property(VM& vm, Object* holder, PropertyKey const& name, FunctionObject& reviver)
{
auto value = TRY(holder->get(name));
if (value.is_object()) {
auto is_array = TRY(value.is_array(vm));
auto& value_object = value.as_object();
auto process_property = [&](PropertyKey const& key) -> ThrowCompletionOr<void> {
auto element = TRY(internalize_json_property(vm, &value_object, key, reviver));
if (element.is_undefined())
TRY(value_object.internal_delete(key));
else
TRY(value_object.create_data_property(key, element));
return {};
};
if (is_array) {
auto length = TRY(length_of_array_like(vm, value_object));
for (size_t i = 0; i < length; ++i)
TRY(process_property(i));
} else {
auto property_list = TRY(value_object.enumerable_own_property_names(Object::PropertyKind::Key));
for (auto& property_key : property_list)
TRY(process_property(property_key.as_string().deprecated_string()));
}
}
return TRY(call(vm, reviver, holder, PrimitiveString::create(vm, name.to_string()), value));
}
}
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