// @ts-check
/**
* @param {unknown} value
*/
const getType = (value) => {
if (value === undefined) return 0
if (value === null) return 1
const t = typeof value
if (t === 'boolean') return 2
if (t === 'number') return 3
if (t === 'string') return 4
if (t === 'object') return 6
if (t === 'bigint') return 9
return -1
}
const RESPONSE_HEADER_SIZE = 16
const RESPONSE_PAYLOAD_SIZE = 10240
const RESPONSE_BUFFER_SIZE = RESPONSE_HEADER_SIZE + RESPONSE_PAYLOAD_SIZE
/**
* @param {Int32Array} sab
* @param {Uint8Array} payload
*/
const writeResponsePayload = (sab, payload) => {
if (payload.length > RESPONSE_PAYLOAD_SIZE) {
throw new RangeError('payload overflow')
}
new Uint8Array(sab.buffer).set(payload, RESPONSE_HEADER_SIZE)
}
/**
* @param {import('memfs').IFs} memfs
* @param {any} value
* @param {ReturnType<typeof getType>} type
* @returns {Uint8Array}
*/
const encodeValue = (memfs, value, type) => {
switch (type) {
case 0:
case 1:
return new Uint8Array(0)
case 2: {
const view = new Int32Array(1)
view[0] = value ? 1 : 0
return new Uint8Array(view.buffer)
}
case 3: {
const view = new Float64Array(1)
view[0] = value
return new Uint8Array(view.buffer)
}
case 4: {
const view = new TextEncoder().encode(value)
return view
}
case 6: {
function storeConstructor(obj, memfs, processed = new WeakSet()) {
if (!obj || typeof obj !== 'object') {
return
}
if (processed.has(obj)) {
return
}
processed.add(obj)
const [entry] =
Object.entries(memfs).filter(([_, v]) => v === obj.constructor)[0] ??
[]
if (entry) {
Object.defineProperty(obj, '__constructor__', {
configurable: true,
writable: true,
enumerable: true,
value: entry,
})
}
for (const value of Object.values(obj)) {
storeConstructor(value, memfs, processed)
}
}
storeConstructor(value, memfs)
const json = JSON.stringify(value, (_, value) => {
if (typeof value === 'bigint') {
return `BigInt(${String(value)})`
}
if (value instanceof Error) {
return {
...value,
message: value.message,
stack: value.stack,
__error__: value.constructor.name,
}
}
return value
})
const view = new TextEncoder().encode(json)
return view
}
case 9: {
return new TextEncoder().encode(String(value))
}
case -1:
default:
throw new Error('unsupported data')
}
}
/**
* @param {typeof import('memfs')} memfs
* @param {Uint8Array} payload
* @param {number} type
* @returns {any}
*/
const decodeValue = (memfs, payload, type) => {
if (type === 0) return undefined
if (type === 1) return null
if (type === 2)
return Boolean(new Int32Array(payload.buffer, payload.byteOffset, 1)[0])
if (type === 3)
return new Float64Array(payload.buffer, payload.byteOffset, 1)[0]
if (type === 4) return new TextDecoder().decode(payload.slice())
if (type === 6) {
const obj = JSON.parse(
new TextDecoder().decode(payload.slice()),
(_key, value) => {
if (typeof value === 'string') {
const matched = value.match(/^BigInt\((-?\d+)\)$/)
if (matched && matched[1]) {
return BigInt(matched[1])
}
}
return value
},
)
function loadConstructor(obj, memfs, processed = new WeakSet()) {
if (!obj || typeof obj !== 'object') {
return
}
if (processed.has(obj)) {
return
}
processed.add(obj)
if (obj.__constructor__) {
const ctor = obj.__constructor__
delete obj.__constructor__
Object.setPrototypeOf(obj, memfs[ctor].prototype)
}
for (const value of Object.values(obj)) {
loadConstructor(value, memfs, processed)
}
}
loadConstructor(obj, memfs)
if (obj.__error__) {
const name = obj.__error__
const ErrorConstructor = globalThis[name] || Error
delete obj.__error__
const err = new ErrorConstructor(obj.message)
Object.defineProperty(err, 'stack', {
configurable: true,
enumerable: false,
writable: true,
value: err.stack,
})
Object.defineProperty(err, Symbol.toStringTag, {
configurable: true,
enumerable: false,
writable: true,
value: name,
})
for (const [k, v] of Object.entries(obj)) {
if (k === 'message' || k === 'stack') continue
err[k] = v
}
return err
}
return obj
}
if (type === 9) {
return BigInt(new TextDecoder().decode(payload.slice()))
}
throw new Error('unsupported data')
}
/**
* @param {import('memfs').IFs} fs
* @returns {(e: { data: { __fs__: { sab: Int32Array, type: keyof import('memfs').IFs, payload: any[] } } }) => void}
*/
// oxlint-disable-next-line no-unused-vars -- fixed in an upcoming release
export const createOnMessage = (fs) =>
function onMessage(e) {
if (e.data.__fs__) {
/**
* 0..4 status(int32_t): 21(waiting) 0(success) 1(error)
* 5..8 type(napi_valuetype): 0(undefined) 1(null) 2(boolean) 3(number) 4(string) 6(jsonstring) 9(bigint) -1(unsupported)
* 9..16 payload_size(uint32_t) <= 10240
* 16..16 + payload_size payload_content
*/
const { sab, type, payload } = e.data.__fs__
const fn = fs[type]
try {
const ret = fn.apply(fs, payload)
const t = getType(ret)
Atomics.store(sab, 1, t)
const v = encodeValue(fs, ret, t)
Atomics.store(sab, 2, v.length)
writeResponsePayload(sab, v)
Atomics.store(sab, 0, 0) // success
} catch (/** @type {any} */ err) {
let t = getType(err)
let v
try {
if (t === -1) {
throw new Error('unsupported data')
}
v = encodeValue(fs, err, t)
} catch {
const fallback = (() => {
try {
return String(err)
} catch {
return 'Unserializable thrown value'
}
})()
t = getType(fallback)
v = encodeValue(fs, fallback, t)
}
if (v.length > RESPONSE_PAYLOAD_SIZE) {
const overflowErr = new RangeError('payload overflow')
t = getType(overflowErr)
v = encodeValue(fs, overflowErr, t)
}
Atomics.store(sab, 1, t)
Atomics.store(sab, 2, v.length)
writeResponsePayload(sab, v)
Atomics.store(sab, 0, 1) // error
} finally {
Atomics.notify(sab, 0)
}
}
}
/**
* @param {typeof import('memfs')} memfs
*/
export const createFsProxy = (memfs) =>
new Proxy(
{},
{
get(_target, p, _receiver) {
/**
* @param {any[]} args
*/
return function (...args) {
const sab = new SharedArrayBuffer(RESPONSE_BUFFER_SIZE)
const i32arr = new Int32Array(sab)
Atomics.store(i32arr, 0, 21)
postMessage({
__fs__: {
sab: i32arr,
type: p,
payload: args,
},
})
Atomics.wait(i32arr, 0, 21)
const status = Atomics.load(i32arr, 0)
const type = Atomics.load(i32arr, 1)
const size = Atomics.load(i32arr, 2)
const content = new Uint8Array(sab, RESPONSE_HEADER_SIZE, size)
const value = decodeValue(memfs, content, type)
if (status === 1) {
throw value
}
return value
}
},
},
)