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wasi.js
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wasi.js
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'use strict';
const {
ArrayPrototypeMap,
ArrayPrototypePush,
FunctionPrototypeBind,
ObjectEntries,
Symbol,
} = primordials;
const {
ERR_INVALID_ARG_TYPE,
ERR_WASI_ALREADY_STARTED
} = require('internal/errors').codes;
const { emitExperimentalWarning } = require('internal/util');
const { isArrayBuffer } = require('internal/util/types');
const {
validateArray,
validateBoolean,
validateInt32,
validateObject,
} = require('internal/validators');
const { WASI: _WASI } = internalBinding('wasi');
const kExitCode = Symbol('kExitCode');
const kSetMemory = Symbol('kSetMemory');
const kStarted = Symbol('kStarted');
const kInstance = Symbol('kInstance');
emitExperimentalWarning('WASI');
function setupInstance(self, instance) {
validateObject(instance, 'instance');
validateObject(instance.exports, 'instance.exports');
// WASI::_SetMemory() in src/node_wasi.cc only expects that |memory| is
// an object. It will try to look up the .buffer property when needed
// and fail with UVWASI_EINVAL when the property is missing or is not
// an ArrayBuffer. Long story short, we don't need much validation here
// but we type-check anyway because it helps catch bugs in the user's
// code early.
validateObject(instance.exports.memory, 'instance.exports.memory');
if (!isArrayBuffer(instance.exports.memory.buffer)) {
throw new ERR_INVALID_ARG_TYPE(
'instance.exports.memory.buffer',
['WebAssembly.Memory'],
instance.exports.memory.buffer);
}
self[kInstance] = instance;
self[kSetMemory](instance.exports.memory);
}
class WASI {
constructor(options = {}) {
validateObject(options, 'options');
if (options.args !== undefined)
validateArray(options.args, 'options.args');
const args = ArrayPrototypeMap(options.args || [], String);
const env = [];
if (options.env !== undefined) {
validateObject(options.env, 'options.env');
for (const [key, value] of ObjectEntries(options.env)) {
if (value !== undefined)
ArrayPrototypePush(env, `${key}=${value}`);
}
}
const preopens = [];
if (options.preopens !== undefined) {
validateObject(options.preopens, 'options.preopens');
for (const [key, value] of ObjectEntries(options.preopens)) {
ArrayPrototypePush(preopens, String(key), String(value));
}
}
const { stdin = 0, stdout = 1, stderr = 2 } = options;
validateInt32(stdin, 'options.stdin', 0);
validateInt32(stdout, 'options.stdout', 0);
validateInt32(stderr, 'options.stderr', 0);
const stdio = [stdin, stdout, stderr];
const wrap = new _WASI(args, env, preopens, stdio);
for (const prop in wrap) {
wrap[prop] = FunctionPrototypeBind(wrap[prop], wrap);
}
if (options.returnOnExit !== undefined) {
validateBoolean(options.returnOnExit, 'options.returnOnExit');
if (options.returnOnExit)
wrap.proc_exit = FunctionPrototypeBind(wasiReturnOnProcExit, this);
}
this[kSetMemory] = wrap._setMemory;
delete wrap._setMemory;
this.wasiImport = wrap;
this[kStarted] = false;
this[kExitCode] = 0;
this[kInstance] = undefined;
}
// Must not export _initialize, must export _start
start(instance) {
if (this[kStarted]) {
throw new ERR_WASI_ALREADY_STARTED();
}
this[kStarted] = true;
setupInstance(this, instance);
const { _start, _initialize } = this[kInstance].exports;
if (typeof _start !== 'function') {
throw new ERR_INVALID_ARG_TYPE(
'instance.exports._start', 'function', _start);
}
if (_initialize !== undefined) {
throw new ERR_INVALID_ARG_TYPE(
'instance.exports._initialize', 'undefined', _initialize);
}
try {
_start();
} catch (err) {
if (err !== kExitCode) {
throw err;
}
}
return this[kExitCode];
}
// Must not export _start, may optionally export _initialize
initialize(instance) {
if (this[kStarted]) {
throw new ERR_WASI_ALREADY_STARTED();
}
this[kStarted] = true;
setupInstance(this, instance);
const { _start, _initialize } = this[kInstance].exports;
if (typeof _initialize !== 'function' && _initialize !== undefined) {
throw new ERR_INVALID_ARG_TYPE(
'instance.exports._initialize', 'function', _initialize);
}
if (_start !== undefined) {
throw new ERR_INVALID_ARG_TYPE(
'instance.exports._start', 'undefined', _initialize);
}
if (_initialize !== undefined) {
_initialize();
}
}
}
module.exports = { WASI };
function wasiReturnOnProcExit(rval) {
// If __wasi_proc_exit() does not terminate the process, an assertion is
// triggered in the wasm runtime. Node can sidestep the assertion and return
// an exit code by recording the exit code, and throwing a JavaScript
// exception that WebAssembly cannot catch.
this[kExitCode] = rval;
throw kExitCode;
}