Shim for the SES StaticModuleRecord and module-to-program transformer
npm install @endo/static-module-recordThis package provides a shim for the StaticModuleRecord constructor, suitable
for use with the SES shim importHook.
The static module record accepts a JavaScript module and converts it into
a form that SES can use to securely emulate JavaScript modules (ESMs, the mjs
file format) with compartments.
``js;
import 'ses';
import { StaticModuleRecord } from '@endo/static-module-record
const c1 = new Compartment({}, {}, {
name: "first compartment",
resolveHook: (moduleSpecifier, moduleReferrer) => {
return resolve(moduleSpecifier, moduleReferrer);
},
importHook: async moduleSpecifier => {
const moduleLocation = locate(moduleSpecifier);
const moduleText = await retrieve(moduleLocation);
return new StaticModuleRecord(moduleText, moduleLocation);
},
});
``
The StaticModuleRecord is a shim for what we hope to eventually call a nativeModuleSource constructor.ModuleSource
However, in the absence of a native , this produces aModuleSource
serializable object that emulates the behavior of in conjunctionCompartment
with the constructor from ses.[[Module]]
A detail that leaks from the implementation is that the constructor rewrites
the source, from an ESM grammar construction to a [[Program]]
construction suitable for confining with the compartment's confined evaluator.
This transform attempts to be unobtrusive, but currently causes some alignment
changes due to (hopefully temporary) limitations to the underlying code
generator.
In the interim, generating a source map can help.
The StaticModuleRecord constructor accepts non-standards-tracksourceMapHook and sourceMapUrl options.
Previously, the sole option was a string argument for the sourceUrl, such
that this would be appended to the generated source.
This change allows for the old or new usage:
`js`
new StaticModuleRecord(source, sourceUrl);
// or
new StaticModuleRecord(source, { sourceUrl, sourceMapUrl, sourceMapHook });
The sourceMapUrl is necessary for generating a source map.
The URL will appear only in the generated source map, so a fully qualified
source map URL is safe and allows for continuity if the map is generated and
debugged on the same host.
This is important because Endo captures precompiled Static Module Records in
bundles, excluding source maps, such that a relative path is not useful.
The sourceMapHook will receive a string source map and a details bag
including:
- source
-
-
Such that the receiver can store the source map somewhere as a side-effect.
Note: the sourceMapHook is synchronous and returns void`.
Exceptions thrown by the hook will propagate up through the constructor. If
the hook returns a promise, it will be dropped and rejections will go uncaught.
If the hook must do async work, these should be queued up as a job that the
caller can later await.
Please help us practice coordinated security bug disclosure, by using the
instructions in
SECURITY.md
to report security-sensitive bugs privately.
For non-security bugs, please use the regular Issues
page.