fix(xsnap): Thread spawn and os into xsnap

Author: kriskowal

packages/xsnap/src/xsnap.js

@@ -1,13 +1,15 @@
 // @ts-check
 /* eslint no-await-in-loop: ["off"] */
 
+/**
+ * @typedef {typeof import('child_process').spawn} Spawn
+ */
+
 /**
  * @template T
  * @typedef {import('./defer').Deferred<T>} Deferred
  */
 
-import { spawn } from 'child_process';
-import { type as getOsType } from 'os';
 import { defer } from './defer';
 import * as netstring from './netstring';
 import * as node from './node-stream';
@@ -18,26 +20,6 @@ const QUERY = '?'.charCodeAt(0);
 
 const importMetaUrl = `file://${__filename}`;
 
-const osType = getOsType();
-const platform = {
-  Linux: 'lin',
-  Darwin: 'mac',
-  Windows_NT: 'win',
-}[osType];
-
-if (platform === undefined) {
-  throw new Error(`xsnap does not support platform ${osType}`);
-}
-
-const xsnapBin = new URL(
-  `../build/bin/${platform}/release/xsnap`,
-  importMetaUrl,
-).pathname;
-const xsnapDebugBin = new URL(
-  `../build/bin/${platform}/debug/xsnap`,
-  importMetaUrl,
-).pathname;
-
 const encoder = new TextEncoder();
 const decoder = new TextDecoder();
 
@@ -51,6 +33,8 @@ function echoSysCall(arg) {
 
 /**
  * @param {Object} options
+ * @param {string} options.os
+ * @param {Spawn} options.spawn
  * @param {(request:Uint8Array) => Promise<Uint8Array>} [options.answerSysCall]
  * @param {string=} [options.name]
  * @param {boolean=} [options.debug]
@@ -60,6 +44,8 @@ function echoSysCall(arg) {
  */
 export function xsnap(options) {
   const {
+    os,
+    spawn,
     name = '<unnamed xsnap worker>',
     answerSysCall = echoSysCall,
     debug = false,
@@ -68,6 +54,25 @@ export function xsnap(options) {
     stderr = 'inherit',
   } = options;
 
+  const platform = {
+    Linux: 'lin',
+    Darwin: 'mac',
+    Windows_NT: 'win',
+  }[os];
+
+  if (platform === undefined) {
+    throw new Error(`xsnap does not support platform ${os}`);
+  }
+
+  const xsnapBin = new URL(
+    `../build/bin/${platform}/release/xsnap`,
+    importMetaUrl,
+  ).pathname;
+  const xsnapDebugBin = new URL(
+    `../build/bin/${platform}/debug/xsnap`,
+    importMetaUrl,
+  ).pathname;
+
   /** @type {Deferred<Error?>} */
   const vatExit = defer();
 

packages/xsnap/src/xsrepl.js

@@ -6,13 +6,20 @@
  * @template T
  * @typedef {import('./defer').Deferred<T>} Deferred
  */
+import * as childProcess from 'child_process';
+import * as os from 'os';
 import * as readline from 'readline';
 import { xsnap } from './xsnap';
 import { defer } from './defer';
 
 const decoder = new TextDecoder();
 
 async function main() {
+  const xsnapOptions = {
+    spawn: childProcess.spawn,
+    os: os.type(),
+  };
+
   /**
    * For the purposes of the REPL, the only syscall is effectively `print`.
    *
@@ -25,11 +32,11 @@ async function main() {
   }
 
   const rl = readline.createInterface({
-    input: process.stdin,
+    input: /** @type {NodeJS.ReadableStream} */ (process.stdin),
     output: process.stdout,
   });
 
-  let vat = xsnap({ answerSysCall });
+  let vat = xsnap({ ...xsnapOptions, answerSysCall });
 
   await vat.evaluate(`
     const compartment = new Compartment();
@@ -60,7 +67,7 @@ async function main() {
     } else if (answer === 'load') {
       const file = await ask('file> ');
       await vat.close();
-      vat = xsnap({ answerSysCall, snapshot: file });
+      vat = xsnap({ ...xsnapOptions, answerSysCall, snapshot: file });
     } else if (answer === 'save') {
       const file = await ask('file> ');
       await vat.snapshot(file);

packages/xsnap/test/test-xsnap.js

@@ -1,18 +1,25 @@
 import test from 'ava';
+import * as childProcess from 'child_process';
+import * as os from 'os';
 import { xsnap } from '../src/xsnap';
 
 const importMetaUrl = `file://${__filename}`;
 
 const decoder = new TextDecoder();
 const encoder = new TextEncoder();
 
+const xsnapOptions = {
+  spawn: childProcess.spawn,
+  os: os.type(),
+};
+
 test('evaluate and sysCall', async t => {
   const messages = [];
   async function answerSysCall(message) {
     messages.push(decoder.decode(message));
     return new Uint8Array();
   }
-  const vat = xsnap({ answerSysCall });
+  const vat = xsnap({ ...xsnapOptions, answerSysCall });
   await vat.evaluate(`sysCall(ArrayBuffer.fromString("Hello, World!"));`);
   await vat.close();
   t.deepEqual(['Hello, World!'], messages);
@@ -24,7 +31,7 @@ test('evaluate until idle', async t => {
     messages.push(decoder.decode(message));
     return new Uint8Array();
   }
-  const vat = xsnap({ answerSysCall });
+  const vat = xsnap({ ...xsnapOptions, answerSysCall });
   await vat.evaluate(`
     (async () => {
       sysCall(ArrayBuffer.fromString("Hello, World!"));
@@ -40,7 +47,7 @@ test('run script until idle', async t => {
     messages.push(decoder.decode(message));
     return new Uint8Array();
   }
-  const vat = xsnap({ answerSysCall });
+  const vat = xsnap({ ...xsnapOptions, answerSysCall });
   await vat.execute(new URL('fixture-xsnap-script.js', importMetaUrl).pathname);
   await vat.close();
   t.deepEqual(['Hello, World!'], messages);
@@ -55,7 +62,7 @@ test('sysCall is synchronous inside, async outside', async t => {
     await Promise.resolve(null);
     return encoder.encode(`${number + 1}`);
   }
-  const vat = xsnap({ answerSysCall });
+  const vat = xsnap({ ...xsnapOptions, answerSysCall });
   await vat.evaluate(`
     const response = sysCall(ArrayBuffer.fromString('0'));
     const number = +String.fromArrayBuffer(response);
@@ -71,7 +78,7 @@ test('deliver a message', async t => {
     messages.push(+decoder.decode(message));
     return new Uint8Array();
   }
-  const vat = xsnap({ answerSysCall });
+  const vat = xsnap({ ...xsnapOptions, answerSysCall });
   await vat.evaluate(`
     function answerSysCall(message) {
       const number = +String.fromArrayBuffer(message);
@@ -91,7 +98,7 @@ test.only('receive a response', async t => {
     messages.push(+decoder.decode(message));
     return new Uint8Array();
   }
-  const vat = xsnap({ answerSysCall });
+  const vat = xsnap({ ...xsnapOptions, answerSysCall });
   await vat.evaluate(`
     function answerSysCall(message) {
       const number = +String.fromArrayBuffer(message);
@@ -116,7 +123,7 @@ test('serialize concurrent messages', async t => {
     messages.push(+decoder.decode(message));
     return new Uint8Array();
   }
-  const vat = xsnap({ answerSysCall });
+  const vat = xsnap({ ...xsnapOptions, answerSysCall });
   await vat.evaluate(`
     globalThis.answerSysCall = message => {
       const number = +String.fromArrayBuffer(message);
@@ -137,14 +144,14 @@ test('write and read snapshot', async t => {
 
   const snapshot = new URL('fixture-snapshot.xss', importMetaUrl).pathname;
 
-  const vat0 = xsnap({ answerSysCall });
+  const vat0 = xsnap({ ...xsnapOptions, answerSysCall });
   await vat0.evaluate(`
     globalThis.hello = "Hello, World!";
   `);
   await vat0.snapshot(snapshot);
   await vat0.close();
 
-  const vat1 = xsnap({ answerSysCall, snapshot });
+  const vat1 = xsnap({ ...xsnapOptions, answerSysCall, snapshot });
   await vat1.evaluate(`
     sysCall(ArrayBuffer.fromString(hello));
   `);