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lib: refactor primordials.makeSafe to use more primordials
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PR-URL: #36865
Reviewed-By: Antoine du Hamel <duhamelantoine1995@gmail.com>
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@ExE-Boss @ruyadorno
ExE-Boss authored and ruyadorno committed Jan 21, 2021
1 parent 64fed31 commit 850d357
Showing 1 changed file with 129 additions and 106 deletions.
235 changes: 129 additions & 106 deletions lib/internal/per_context/primordials.js
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Expand Up @@ -6,6 +6,12 @@
// so that Node.js's builtin modules do not need to later look these up from
// the global proxy, which can be mutated by users.

const {
defineProperty: ReflectDefineProperty,
getOwnPropertyDescriptor: ReflectGetOwnPropertyDescriptor,
ownKeys: ReflectOwnKeys,
} = Reflect;

// TODO(joyeecheung): we can restrict access to these globals in builtin
// modules through the JS linter, for example: ban access such as `Object`
// (which falls back to a lookup in the global proxy) in favor of
Expand All @@ -19,159 +25,66 @@ const { bind, call } = Function.prototype;
const uncurryThis = bind.bind(call);
primordials.uncurryThis = uncurryThis;

function copyProps(src, dest) {
for (const key of Reflect.ownKeys(src)) {
if (!Reflect.getOwnPropertyDescriptor(dest, key)) {
Reflect.defineProperty(
dest,
key,
Reflect.getOwnPropertyDescriptor(src, key));
}
}
}

function getNewKey(key) {
return typeof key === 'symbol' ?
`Symbol${key.description[7].toUpperCase()}${key.description.slice(8)}` :
`${key[0].toUpperCase()}${key.slice(1)}`;
}

function copyAccessor(dest, prefix, key, { enumerable, get, set }) {
Reflect.defineProperty(dest, `${prefix}Get${key}`, {
ReflectDefineProperty(dest, `${prefix}Get${key}`, {
value: uncurryThis(get),
enumerable
});
if (set !== undefined) {
Reflect.defineProperty(dest, `${prefix}Set${key}`, {
ReflectDefineProperty(dest, `${prefix}Set${key}`, {
value: uncurryThis(set),
enumerable
});
}
}

function copyPropsRenamed(src, dest, prefix) {
for (const key of Reflect.ownKeys(src)) {
for (const key of ReflectOwnKeys(src)) {
const newKey = getNewKey(key);
const desc = Reflect.getOwnPropertyDescriptor(src, key);
const desc = ReflectGetOwnPropertyDescriptor(src, key);
if ('get' in desc) {
copyAccessor(dest, prefix, newKey, desc);
} else {
Reflect.defineProperty(dest, `${prefix}${newKey}`, desc);
ReflectDefineProperty(dest, `${prefix}${newKey}`, desc);
}
}
}

function copyPropsRenamedBound(src, dest, prefix) {
for (const key of Reflect.ownKeys(src)) {
for (const key of ReflectOwnKeys(src)) {
const newKey = getNewKey(key);
const desc = Reflect.getOwnPropertyDescriptor(src, key);
const desc = ReflectGetOwnPropertyDescriptor(src, key);
if ('get' in desc) {
copyAccessor(dest, prefix, newKey, desc);
} else {
if (typeof desc.value === 'function') {
desc.value = desc.value.bind(src);
}
Reflect.defineProperty(dest, `${prefix}${newKey}`, desc);
ReflectDefineProperty(dest, `${prefix}${newKey}`, desc);
}
}
}

function copyPrototype(src, dest, prefix) {
for (const key of Reflect.ownKeys(src)) {
for (const key of ReflectOwnKeys(src)) {
const newKey = getNewKey(key);
const desc = Reflect.getOwnPropertyDescriptor(src, key);
const desc = ReflectGetOwnPropertyDescriptor(src, key);
if ('get' in desc) {
copyAccessor(dest, prefix, newKey, desc);
} else {
if (typeof desc.value === 'function') {
desc.value = uncurryThis(desc.value);
}
Reflect.defineProperty(dest, `${prefix}${newKey}`, desc);
}
}
}

const createSafeIterator = (factory, next) => {
class SafeIterator {
constructor(iterable) {
this._iterator = factory(iterable);
}
next() {
return next(this._iterator);
}
[Symbol.iterator]() {
return this;
}
}
Object.setPrototypeOf(SafeIterator.prototype, null);
Object.freeze(SafeIterator.prototype);
Object.freeze(SafeIterator);
return SafeIterator;
};

function makeSafe(unsafe, safe) {
if (Symbol.iterator in unsafe.prototype) {
const dummy = new unsafe();
let next; // We can reuse the same `next` method.

for (const key of Reflect.ownKeys(unsafe.prototype)) {
if (!Reflect.getOwnPropertyDescriptor(safe.prototype, key)) {
const desc = Reflect.getOwnPropertyDescriptor(unsafe.prototype, key);
if (
typeof desc.value === 'function' &&
desc.value.length === 0 &&
Symbol.iterator in (desc.value.call(dummy) ?? {})
) {
const createIterator = uncurryThis(desc.value);
next ??= uncurryThis(createIterator(dummy).next);
const SafeIterator = createSafeIterator(createIterator, next);
desc.value = function() {
return new SafeIterator(this);
};
}
Reflect.defineProperty(safe.prototype, key, desc);
}
ReflectDefineProperty(dest, `${prefix}${newKey}`, desc);
}
} else {
copyProps(unsafe.prototype, safe.prototype);
}
copyProps(unsafe, safe);

Object.setPrototypeOf(safe.prototype, null);
Object.freeze(safe.prototype);
Object.freeze(safe);
return safe;
}
primordials.makeSafe = makeSafe;

// Subclass the constructors because we need to use their prototype
// methods later.
// Defining the `constructor` is necessary here to avoid the default
// constructor which uses the user-mutable `%ArrayIteratorPrototype%.next`.
primordials.SafeMap = makeSafe(
Map,
class SafeMap extends Map {
constructor(i) { super(i); } // eslint-disable-line no-useless-constructor
}
);
primordials.SafeWeakMap = makeSafe(
WeakMap,
class SafeWeakMap extends WeakMap {
constructor(i) { super(i); } // eslint-disable-line no-useless-constructor
}
);
primordials.SafeSet = makeSafe(
Set,
class SafeSet extends Set {
constructor(i) { super(i); } // eslint-disable-line no-useless-constructor
}
);
primordials.SafeWeakSet = makeSafe(
WeakSet,
class SafeWeakSet extends WeakSet {
constructor(i) { super(i); } // eslint-disable-line no-useless-constructor
}
);

// Create copies of the namespace objects
[
Expand Down Expand Up @@ -256,6 +169,41 @@ primordials.SafeWeakSet = makeSafe(
copyPrototype(original.prototype, primordials, `${name}Prototype`);
});

/* eslint-enable node-core/prefer-primordials */

const {
ArrayPrototypeForEach,
FunctionPrototypeCall,
Map,
ObjectFreeze,
ObjectSetPrototypeOf,
Set,
SymbolIterator,
WeakMap,
WeakSet,
} = primordials;

// Because these functions are used by `makeSafe`, which is exposed
// on the `primordials` object, it's important to use const references
// to the primordials that they use:
const createSafeIterator = (factory, next) => {
class SafeIterator {
constructor(iterable) {
this._iterator = factory(iterable);
}
next() {
return next(this._iterator);
}
[SymbolIterator]() {
return this;
}
}
ObjectSetPrototypeOf(SafeIterator.prototype, null);
ObjectFreeze(SafeIterator.prototype);
ObjectFreeze(SafeIterator);
return SafeIterator;
};

primordials.SafeArrayIterator = createSafeIterator(
primordials.ArrayPrototypeSymbolIterator,
primordials.ArrayIteratorPrototypeNext
Expand All @@ -265,5 +213,80 @@ primordials.SafeStringIterator = createSafeIterator(
primordials.StringIteratorPrototypeNext
);

Object.setPrototypeOf(primordials, null);
Object.freeze(primordials);
const copyProps = (src, dest) => {
ArrayPrototypeForEach(ReflectOwnKeys(src), (key) => {
if (!ReflectGetOwnPropertyDescriptor(dest, key)) {
ReflectDefineProperty(
dest,
key,
ReflectGetOwnPropertyDescriptor(src, key));
}
});
};

const makeSafe = (unsafe, safe) => {
if (SymbolIterator in unsafe.prototype) {
const dummy = new unsafe();
let next; // We can reuse the same `next` method.

ArrayPrototypeForEach(ReflectOwnKeys(unsafe.prototype), (key) => {
if (!ReflectGetOwnPropertyDescriptor(safe.prototype, key)) {
const desc = ReflectGetOwnPropertyDescriptor(unsafe.prototype, key);
if (
typeof desc.value === 'function' &&
desc.value.length === 0 &&
SymbolIterator in (FunctionPrototypeCall(desc.value, dummy) ?? {})
) {
const createIterator = uncurryThis(desc.value);
next ??= uncurryThis(createIterator(dummy).next);
const SafeIterator = createSafeIterator(createIterator, next);
desc.value = function() {
return new SafeIterator(this);
};
}
ReflectDefineProperty(safe.prototype, key, desc);
}
});
} else {
copyProps(unsafe.prototype, safe.prototype);
}
copyProps(unsafe, safe);

ObjectSetPrototypeOf(safe.prototype, null);
ObjectFreeze(safe.prototype);
ObjectFreeze(safe);
return safe;
};
primordials.makeSafe = makeSafe;

// Subclass the constructors because we need to use their prototype
// methods later.
// Defining the `constructor` is necessary here to avoid the default
// constructor which uses the user-mutable `%ArrayIteratorPrototype%.next`.
primordials.SafeMap = makeSafe(
Map,
class SafeMap extends Map {
constructor(i) { super(i); } // eslint-disable-line no-useless-constructor
}
);
primordials.SafeWeakMap = makeSafe(
WeakMap,
class SafeWeakMap extends WeakMap {
constructor(i) { super(i); } // eslint-disable-line no-useless-constructor
}
);
primordials.SafeSet = makeSafe(
Set,
class SafeSet extends Set {
constructor(i) { super(i); } // eslint-disable-line no-useless-constructor
}
);
primordials.SafeWeakSet = makeSafe(
WeakSet,
class SafeWeakSet extends WeakSet {
constructor(i) { super(i); } // eslint-disable-line no-useless-constructor
}
);

ObjectSetPrototypeOf(primordials, null);
ObjectFreeze(primordials);

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