Skip to content

Commit 8f8d5cf

Browse files
erightserights
committed
feat(no-trapping-shim): Ponyfill and shim for noTrapping integrity level
1 parent 215eaf4 commit 8f8d5cf

File tree

7 files changed

+286
-6
lines changed

7 files changed

+286
-6
lines changed

‎packages/no-trapping-shim/package.json

-1
Original file line numberDiff line numberDiff line change
@@ -35,7 +35,6 @@
3535
"test:c8": "c8 $C8_OPTIONS ava --config=ava-nesm.config.js",
3636
"test:xs": "exit 0"
3737
},
38-
"dependencies": {},
3938
"devDependencies": {
4039
"@endo/lockdown": "workspace:^",
4140
"@endo/ses-ava": "workspace:^",

‎packages/no-trapping-shim/src/no-trapping-pony.js

+206
Original file line numberDiff line numberDiff line change
@@ -0,0 +1,206 @@
1+
const OriginalObject = Object;
2+
const OriginalReflect = Reflect;
3+
const OriginalProxy = Proxy;
4+
const { freeze, defineProperty } = OriginalObject;
5+
const { apply, construct, ownKeys } = OriginalReflect;
6+
7+
const noTrappingSet = new WeakSet();
8+
9+
const proxyHandlerMap = new WeakMap();
10+
11+
const isPrimitive = specimen => OriginalObject(specimen) !== specimen;
12+
13+
/**
14+
* Corresponds to the internal function shared by `Object.isNoTrapping` and
15+
* `Reflect.isNoTrapping`.
16+
*
17+
* @param {any} specimen
18+
* @param {boolean} shouldThrow
19+
* @returns {boolean}
20+
*/
21+
const isNoTrappingInternal = (specimen, shouldThrow) => {
22+
if (noTrappingSet.has(specimen)) {
23+
return true;
24+
}
25+
if (!proxyHandlerMap.has(specimen)) {
26+
return false;
27+
}
28+
const [target, handler] = proxyHandlerMap.get(specimen);
29+
if (isNoTrappingInternal(target, shouldThrow)) {
30+
noTrappingSet.add(specimen);
31+
return true;
32+
}
33+
const trap = handler.isNoTrapping;
34+
if (trap === undefined) {
35+
return false;
36+
}
37+
const result = apply(trap, handler, [target]);
38+
const ofTarget = isNoTrappingInternal(target, shouldThrow);
39+
if (result !== ofTarget) {
40+
if (shouldThrow) {
41+
throw TypeError(
42+
`'isNoTrapping' proxy trap does not reflect 'isNoTrapping' of proxy target (which is '${ofTarget}')`,
43+
);
44+
}
45+
return false;
46+
}
47+
if (result) {
48+
noTrappingSet.add(specimen);
49+
}
50+
return result;
51+
};
52+
53+
/**
54+
* Corresponds to the internal function shared by `Object.suppressTrapping` and
55+
* `Reflect.suppressTrapping`.
56+
*
57+
* @param {any} specimen
58+
* @param {boolean} shouldThrow
59+
* @returns {boolean}
60+
*/
61+
const suppressTrappingInternal = (specimen, shouldThrow) => {
62+
if (noTrappingSet.has(specimen)) {
63+
return true;
64+
}
65+
freeze(specimen);
66+
if (!proxyHandlerMap.has(specimen)) {
67+
noTrappingSet.add(specimen);
68+
return true;
69+
}
70+
const [target, handler] = proxyHandlerMap.get(specimen);
71+
if (isNoTrappingInternal(target, shouldThrow)) {
72+
noTrappingSet.add(specimen);
73+
return true;
74+
}
75+
const trap = handler.suppressTrapping;
76+
if (trap === undefined) {
77+
const result = suppressTrappingInternal(target, shouldThrow);
78+
if (result) {
79+
noTrappingSet.add(specimen);
80+
}
81+
return result;
82+
}
83+
const result = apply(trap, handler, [target]);
84+
const ofTarget = isNoTrappingInternal(target, shouldThrow);
85+
if (result !== ofTarget) {
86+
if (shouldThrow) {
87+
throw TypeError(
88+
`'suppressTrapping' proxy trap does not reflect 'isNoTrapping' of proxy target (which is '${ofTarget}')`,
89+
);
90+
}
91+
return false;
92+
}
93+
if (result) {
94+
noTrappingSet.add(specimen);
95+
}
96+
return result;
97+
};
98+
99+
export const extraReflectMethods = freeze({
100+
isNoTrapping(target) {
101+
if (isPrimitive(target)) {
102+
throw TypeError('Reflect.isNoTrapping called on non-object');
103+
}
104+
return isNoTrappingInternal(target, false);
105+
},
106+
suppressTrapping(target) {
107+
if (isPrimitive(target)) {
108+
throw TypeError('Reflect.suppressTrapping called on non-object');
109+
}
110+
return suppressTrappingInternal(target, false);
111+
},
112+
});
113+
114+
export const extraObjectMethods = freeze({
115+
isNoTrapping(target) {
116+
if (isPrimitive(target)) {
117+
return true;
118+
}
119+
return isNoTrappingInternal(target, true);
120+
},
121+
suppressTrapping(target) {
122+
if (isPrimitive(target)) {
123+
return target;
124+
}
125+
if (suppressTrappingInternal(target, true)) {
126+
return target;
127+
}
128+
throw TypeError('preventExtensions trap returned falsy');
129+
},
130+
});
131+
132+
const addExtras = (base, ...extrasArgs) => {
133+
for (const extras of extrasArgs) {
134+
for (const key of ownKeys(extras)) {
135+
if (base[key] !== extras[key]) {
136+
defineProperty(base, key, {
137+
value: extras[key],
138+
writable: true,
139+
enumerable: false,
140+
configurable: true,
141+
});
142+
}
143+
}
144+
}
145+
};
146+
147+
const ReflectPlus = {};
148+
addExtras(ReflectPlus, OriginalReflect, extraReflectMethods);
149+
export { ReflectPlus };
150+
151+
const ObjectPlus = function Object(...args) {
152+
if (new.target) {
153+
return construct(OriginalObject, args, new.target);
154+
} else {
155+
return apply(OriginalObject, this, args);
156+
}
157+
};
158+
ObjectPlus.prototype = OriginalObject.prototype;
159+
addExtras(ObjectPlus, OriginalObject, extraObjectMethods);
160+
export { ObjectPlus };
161+
162+
const makeMetaHandler = handler =>
163+
freeze({
164+
get(_, trapName, _receiver) {
165+
return freeze((target, ...rest) => {
166+
if (
167+
isNoTrappingInternal(target, true) ||
168+
handler[trapName] === undefined
169+
) {
170+
return ReflectPlus[trapName](target, ...rest);
171+
} else {
172+
return handler[trapName](target, ...rest);
173+
}
174+
});
175+
},
176+
});
177+
178+
const makeSafeHandler = handler =>
179+
new OriginalProxy({}, makeMetaHandler(handler));
180+
181+
/**
182+
* In the shim, `ProxyPlus` should replace the global `Proxy`.
183+
*
184+
* @param {any} target
185+
* @param {object} handler
186+
*/
187+
const ProxyPlus = function Proxy(target, handler) {
188+
if (new.target !== ProxyPlus) {
189+
if (new.target === undefined) {
190+
throw TypeError('Proxy constructor requires "new"');
191+
}
192+
throw TypeError('Safe Proxy shim does not support subclassing');
193+
}
194+
const safeHandler = makeSafeHandler(handler);
195+
const proxy = new OriginalProxy(target, safeHandler);
196+
proxyHandlerMap.set(proxy, [target, handler]);
197+
return proxy;
198+
};
199+
ProxyPlus.revocable = (target, handler) => {
200+
const safeHandler = makeSafeHandler(handler);
201+
const { proxy, revoke } = OriginalProxy.revocable(target, safeHandler);
202+
proxyHandlerMap.set(proxy, [target, handler]);
203+
return { proxy, revoke };
204+
};
205+
206+
export { ProxyPlus };

‎packages/no-trapping-shim/src/no-trapping-shim.js

+12
Original file line numberDiff line numberDiff line change
@@ -0,0 +1,12 @@
1+
/* global globalThis */
2+
import { ReflectPlus, ObjectPlus, ProxyPlus } from './no-trapping-pony.js';
3+
4+
globalThis.Reflect = ReflectPlus;
5+
6+
// @ts-expect-error Something about the type of the Object constructor
7+
globalThis.Object = ObjectPlus;
8+
// eslint-disable-next-line no-extend-native
9+
Object.prototype.constructor = ObjectPlus;
10+
11+
// @ts-expect-error Something about the type of Proxy
12+
globalThis.Proxy = ProxyPlus;

‎packages/no-trapping-shim/test/index.test.js

-5
This file was deleted.

‎packages/no-trapping-shim/test/no-trapping-pony.test.js

+26
Original file line numberDiff line numberDiff line change
@@ -0,0 +1,26 @@
1+
import test from '@endo/ses-ava/prepare-endo.js';
2+
import { ReflectPlus, ProxyPlus } from '../src/no-trapping-pony.js';
3+
4+
const { freeze, isFrozen } = Object;
5+
6+
test('no-trapping-pony', async t => {
7+
const specimen = { foo: 8 };
8+
9+
const sillyHandler = freeze({
10+
get(target, prop, receiver) {
11+
return [target, prop, receiver];
12+
},
13+
});
14+
15+
const safeProxy = new ProxyPlus(specimen, sillyHandler);
16+
17+
t.false(ReflectPlus.isNoTrapping(specimen));
18+
t.false(isFrozen(specimen));
19+
t.deepEqual(safeProxy.foo, [specimen, 'foo', safeProxy]);
20+
21+
t.true(ReflectPlus.suppressTrapping(specimen));
22+
23+
t.true(ReflectPlus.isNoTrapping(specimen));
24+
t.true(isFrozen(specimen));
25+
t.deepEqual(safeProxy.foo, 8);
26+
});

‎packages/no-trapping-shim/test/no-trapping-shim.test.js

+29
Original file line numberDiff line numberDiff line change
@@ -0,0 +1,29 @@
1+
import '../src/no-trapping-shim.js';
2+
// TODO make compat with ses and uncomment
3+
// import test from '@endo/ses-ava/prepare-endo.js';
4+
// instead of
5+
import test from 'ava';
6+
7+
const { freeze, isFrozen } = Object;
8+
9+
test('no-trapping-pony', async t => {
10+
const specimen = { foo: 8 };
11+
12+
const sillyHandler = freeze({
13+
get(target, prop, receiver) {
14+
return [target, prop, receiver];
15+
},
16+
});
17+
18+
const safeProxy = new Proxy(specimen, sillyHandler);
19+
20+
t.false(Reflect.isNoTrapping(specimen));
21+
t.false(isFrozen(specimen));
22+
t.deepEqual(safeProxy.foo, [specimen, 'foo', safeProxy]);
23+
24+
t.true(Reflect.suppressTrapping(specimen));
25+
26+
t.true(Reflect.isNoTrapping(specimen));
27+
t.true(isFrozen(specimen));
28+
t.deepEqual(safeProxy.foo, 8);
29+
});

‎yarn.lock

+13
Original file line numberDiff line numberDiff line change
@@ -702,6 +702,19 @@ __metadata:
702702
languageName: unknown
703703
linkType: soft
704704

705+
"@endo/no-trapping-shim@workspace:packages/no-trapping-shim":
706+
version: 0.0.0-use.local
707+
resolution: "@endo/no-trapping-shim@workspace:packages/no-trapping-shim"
708+
dependencies:
709+
"@endo/lockdown": "workspace:^"
710+
"@endo/ses-ava": "workspace:^"
711+
ava: "npm:^6.1.3"
712+
c8: "npm:^7.14.0"
713+
tsd: "npm:^0.31.2"
714+
typescript: "npm:~5.6.3"
715+
languageName: unknown
716+
linkType: soft
717+
705718
"@endo/pass-style@workspace:^, @endo/pass-style@workspace:packages/pass-style":
706719
version: 0.0.0-use.local
707720
resolution: "@endo/pass-style@workspace:packages/pass-style"

0 commit comments

Comments
 (0)