511 lines
14 KiB
JavaScript
511 lines
14 KiB
JavaScript
/*
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MIT License http://www.opensource.org/licenses/mit-license.php
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*/
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"use strict";
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const { constants } = require("buffer");
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const createHash = require("../util/createHash");
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const { dirname, join, mkdirp } = require("../util/fs");
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const memoize = require("../util/memoize");
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const SerializerMiddleware = require("./SerializerMiddleware");
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/** @typedef {import("../util/fs").IntermediateFileSystem} IntermediateFileSystem */
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/** @typedef {import("./types").BufferSerializableType} BufferSerializableType */
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/*
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Format:
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File -> Header Section*
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Version -> u32
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AmountOfSections -> u32
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SectionSize -> i32 (if less than zero represents lazy value)
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Header -> Version AmountOfSections SectionSize*
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Buffer -> n bytes
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Section -> Buffer
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*/
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// "wpc" + 1 in little-endian
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const VERSION = 0x01637077;
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const hashForName = buffers => {
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const hash = createHash("md4");
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for (const buf of buffers) hash.update(buf);
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return /** @type {string} */ (hash.digest("hex"));
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};
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const writeUInt64LE = Buffer.prototype.writeBigUInt64LE
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? (buf, value, offset) => {
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buf.writeBigUInt64LE(BigInt(value), offset);
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}
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: (buf, value, offset) => {
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const low = value % 0x100000000;
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const high = (value - low) / 0x100000000;
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buf.writeUInt32LE(low, offset);
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buf.writeUInt32LE(high, offset + 4);
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};
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const readUInt64LE = Buffer.prototype.readBigUInt64LE
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? (buf, offset) => {
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return Number(buf.readBigUInt64LE(offset));
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}
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: (buf, offset) => {
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const low = buf.readUInt32LE(offset);
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const high = buf.readUInt32LE(offset + 4);
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return high * 0x100000000 + low;
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};
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/**
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* @typedef {Object} SerializeResult
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* @property {string | false} name
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* @property {number} size
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* @property {Promise=} backgroundJob
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*/
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/**
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* @param {FileMiddleware} middleware this
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* @param {BufferSerializableType[] | Promise<BufferSerializableType[]>} data data to be serialized
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* @param {string | boolean} name file base name
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* @param {function(string | false, Buffer[]): Promise} writeFile writes a file
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* @returns {Promise<SerializeResult>} resulting file pointer and promise
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*/
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const serialize = async (middleware, data, name, writeFile) => {
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/** @type {(Buffer[] | Buffer | SerializeResult | Promise<SerializeResult>)[]} */
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const processedData = [];
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/** @type {WeakMap<SerializeResult, function(): any | Promise<any>>} */
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const resultToLazy = new WeakMap();
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/** @type {Buffer[]} */
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let lastBuffers = undefined;
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for (const item of await data) {
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if (typeof item === "function") {
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if (!SerializerMiddleware.isLazy(item))
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throw new Error("Unexpected function");
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if (!SerializerMiddleware.isLazy(item, middleware)) {
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throw new Error(
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"Unexpected lazy value with non-this target (can't pass through lazy values)"
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);
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}
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lastBuffers = undefined;
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const serializedInfo = SerializerMiddleware.getLazySerializedValue(item);
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if (serializedInfo) {
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if (typeof serializedInfo === "function") {
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throw new Error(
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"Unexpected lazy value with non-this target (can't pass through lazy values)"
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);
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} else {
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processedData.push(serializedInfo);
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}
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} else {
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const content = item();
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if (content) {
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const options = SerializerMiddleware.getLazyOptions(item);
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processedData.push(
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serialize(
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middleware,
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content,
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(options && options.name) || true,
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writeFile
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).then(result => {
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/** @type {any} */ (item).options.size = result.size;
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resultToLazy.set(result, item);
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return result;
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})
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);
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} else {
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throw new Error(
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"Unexpected falsy value returned by lazy value function"
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);
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}
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}
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} else if (item) {
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if (lastBuffers) {
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lastBuffers.push(item);
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} else {
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lastBuffers = [item];
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processedData.push(lastBuffers);
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}
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} else {
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throw new Error("Unexpected falsy value in items array");
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}
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}
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/** @type {Promise<any>[]} */
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const backgroundJobs = [];
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const resolvedData = (
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await Promise.all(
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/** @type {Promise<Buffer[] | Buffer | SerializeResult>[]} */ (processedData)
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)
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).map(item => {
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if (Array.isArray(item) || Buffer.isBuffer(item)) return item;
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backgroundJobs.push(item.backgroundJob);
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// create pointer buffer from size and name
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const name = /** @type {string} */ (item.name);
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const nameBuffer = Buffer.from(name);
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const buf = Buffer.allocUnsafe(8 + nameBuffer.length);
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writeUInt64LE(buf, item.size, 0);
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nameBuffer.copy(buf, 8, 0);
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const lazy = resultToLazy.get(item);
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SerializerMiddleware.setLazySerializedValue(lazy, buf);
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return buf;
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});
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const lengths = [];
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for (const item of resolvedData) {
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if (Array.isArray(item)) {
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let l = 0;
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for (const b of item) l += b.length;
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while (l > 0x7fffffff) {
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lengths.push(0x7fffffff);
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l -= 0x7fffffff;
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}
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lengths.push(l);
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} else if (item) {
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lengths.push(-item.length);
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} else {
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throw new Error("Unexpected falsy value in resolved data " + item);
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}
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}
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const header = Buffer.allocUnsafe(8 + lengths.length * 4);
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header.writeUInt32LE(VERSION, 0);
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header.writeUInt32LE(lengths.length, 4);
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for (let i = 0; i < lengths.length; i++) {
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header.writeInt32LE(lengths[i], 8 + i * 4);
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}
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const buf = [header];
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for (const item of resolvedData) {
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if (Array.isArray(item)) {
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for (const b of item) buf.push(b);
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} else if (item) {
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buf.push(item);
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}
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}
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if (name === true) {
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name = hashForName(buf);
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}
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backgroundJobs.push(writeFile(name, buf));
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let size = 0;
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for (const b of buf) size += b.length;
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return {
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size,
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name,
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backgroundJob:
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backgroundJobs.length === 1
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? backgroundJobs[0]
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: Promise.all(backgroundJobs)
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};
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};
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/**
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* @param {FileMiddleware} middleware this
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* @param {string | false} name filename
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* @param {function(string | false): Promise<Buffer[]>} readFile read content of a file
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* @returns {Promise<BufferSerializableType[]>} deserialized data
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*/
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const deserialize = async (middleware, name, readFile) => {
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const contents = await readFile(name);
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if (contents.length === 0) throw new Error("Empty file " + name);
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let contentsIndex = 0;
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let contentItem = contents[0];
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let contentItemLength = contentItem.length;
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let contentPosition = 0;
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if (contentItemLength === 0) throw new Error("Empty file " + name);
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const nextContent = () => {
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contentsIndex++;
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contentItem = contents[contentsIndex];
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contentItemLength = contentItem.length;
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contentPosition = 0;
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};
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const ensureData = n => {
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if (contentPosition === contentItemLength) {
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nextContent();
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}
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while (contentItemLength - contentPosition < n) {
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const remaining = contentItem.slice(contentPosition);
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let lengthFromNext = n - remaining.length;
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const buffers = [remaining];
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for (let i = contentsIndex + 1; i < contents.length; i++) {
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const l = contents[i].length;
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if (l > lengthFromNext) {
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buffers.push(contents[i].slice(0, lengthFromNext));
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contents[i] = contents[i].slice(lengthFromNext);
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lengthFromNext = 0;
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break;
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} else {
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buffers.push(contents[i]);
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contentsIndex = i;
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lengthFromNext -= l;
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}
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}
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if (lengthFromNext > 0) throw new Error("Unexpected end of data");
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contentItem = Buffer.concat(buffers, n);
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contentItemLength = n;
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contentPosition = 0;
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}
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};
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const readUInt32LE = () => {
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ensureData(4);
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const value = contentItem.readUInt32LE(contentPosition);
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contentPosition += 4;
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return value;
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};
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const readInt32LE = () => {
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ensureData(4);
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const value = contentItem.readInt32LE(contentPosition);
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contentPosition += 4;
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return value;
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};
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const readSlice = l => {
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ensureData(l);
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if (contentPosition === 0 && contentItemLength === l) {
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const result = contentItem;
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if (contentsIndex + 1 < contents.length) {
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nextContent();
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} else {
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contentPosition = l;
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}
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return result;
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}
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const result = contentItem.slice(contentPosition, contentPosition + l);
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contentPosition += l;
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// we clone the buffer here to allow the original content to be garbage collected
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return l * 2 < contentItem.buffer.byteLength ? Buffer.from(result) : result;
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};
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const version = readUInt32LE();
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if (version !== VERSION) {
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throw new Error("Invalid file version");
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}
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const sectionCount = readUInt32LE();
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const lengths = [];
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for (let i = 0; i < sectionCount; i++) {
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lengths.push(readInt32LE());
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}
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const result = [];
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for (let length of lengths) {
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if (length < 0) {
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const slice = readSlice(-length);
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const size = Number(readUInt64LE(slice, 0));
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const nameBuffer = slice.slice(8);
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const name = nameBuffer.toString();
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result.push(
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SerializerMiddleware.createLazy(
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memoize(() => deserialize(middleware, name, readFile)),
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middleware,
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{
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name,
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size
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},
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slice
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)
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);
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} else {
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if (contentPosition === contentItemLength) {
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nextContent();
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} else if (contentPosition !== 0) {
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if (length <= contentItemLength - contentPosition) {
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result.push(
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contentItem.slice(contentPosition, contentPosition + length)
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);
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contentPosition += length;
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length = 0;
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} else {
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result.push(contentItem.slice(contentPosition));
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length -= contentItemLength - contentPosition;
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contentPosition = contentItemLength;
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}
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} else {
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if (length >= contentItemLength) {
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result.push(contentItem);
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length -= contentItemLength;
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contentPosition = contentItemLength;
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} else {
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result.push(contentItem.slice(0, length));
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contentPosition += length;
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length = 0;
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}
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}
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while (length > 0) {
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nextContent();
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if (length >= contentItemLength) {
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result.push(contentItem);
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length -= contentItemLength;
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contentPosition = contentItemLength;
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} else {
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result.push(contentItem.slice(0, length));
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contentPosition += length;
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length = 0;
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}
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}
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}
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}
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return result;
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};
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/**
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* @typedef {BufferSerializableType[]} DeserializedType
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* @typedef {true} SerializedType
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* @extends {SerializerMiddleware<DeserializedType, SerializedType>}
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*/
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class FileMiddleware extends SerializerMiddleware {
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/**
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* @param {IntermediateFileSystem} fs filesystem
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*/
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constructor(fs) {
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super();
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this.fs = fs;
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}
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/**
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* @param {DeserializedType} data data
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* @param {Object} context context object
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* @returns {SerializedType|Promise<SerializedType>} serialized data
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*/
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serialize(data, context) {
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const { filename, extension = "" } = context;
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return new Promise((resolve, reject) => {
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mkdirp(this.fs, dirname(this.fs, filename), err => {
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if (err) return reject(err);
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// It's important that we don't touch existing files during serialization
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// because serialize may read existing files (when deserializing)
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const allWrittenFiles = new Set();
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const writeFile = async (name, content) => {
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const file = name
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? join(this.fs, filename, `../${name}${extension}`)
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: filename;
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await new Promise((resolve, reject) => {
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const stream = this.fs.createWriteStream(file + "_");
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for (const b of content) stream.write(b);
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stream.end();
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stream.on("error", err => reject(err));
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stream.on("finish", () => resolve());
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});
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if (name) allWrittenFiles.add(file);
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};
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resolve(
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serialize(this, data, false, writeFile).then(
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async ({ backgroundJob }) => {
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await backgroundJob;
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// Rename the index file to disallow access during inconsistent file state
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await new Promise(resolve =>
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this.fs.rename(filename, filename + ".old", err => {
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resolve();
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})
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);
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// update all written files
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await Promise.all(
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Array.from(
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allWrittenFiles,
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file =>
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new Promise((resolve, reject) => {
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this.fs.rename(file + "_", file, err => {
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if (err) return reject(err);
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resolve();
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});
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})
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)
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);
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// As final step automatically update the index file to have a consistent pack again
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await new Promise(resolve => {
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this.fs.rename(filename + "_", filename, err => {
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if (err) return reject(err);
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resolve();
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});
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});
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return /** @type {true} */ (true);
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}
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)
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);
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});
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});
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}
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/**
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* @param {SerializedType} data data
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* @param {Object} context context object
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* @returns {DeserializedType|Promise<DeserializedType>} deserialized data
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*/
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deserialize(data, context) {
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const { filename, extension = "" } = context;
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const readFile = name =>
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new Promise((resolve, reject) => {
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const file = name
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? join(this.fs, filename, `../${name}${extension}`)
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: filename;
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this.fs.stat(file, (err, stats) => {
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if (err) {
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reject(err);
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return;
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}
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let remaining = /** @type {number} */ (stats.size);
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let currentBuffer;
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let currentBufferUsed;
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const buf = [];
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this.fs.open(file, "r", (err, fd) => {
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if (err) {
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reject(err);
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return;
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}
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const read = () => {
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if (currentBuffer === undefined) {
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currentBuffer = Buffer.allocUnsafeSlow(
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Math.min(constants.MAX_LENGTH, remaining)
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);
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currentBufferUsed = 0;
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}
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let readBuffer = currentBuffer;
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let readOffset = currentBufferUsed;
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let readLength = currentBuffer.length - currentBufferUsed;
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if (readOffset > 0x7fffffff) {
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readBuffer = currentBuffer.slice(readOffset);
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readOffset = 0;
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}
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if (readLength > 0x7fffffff) {
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readLength = 0x7fffffff;
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}
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this.fs.read(
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fd,
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readBuffer,
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readOffset,
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readLength,
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null,
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(err, bytesRead) => {
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if (err) {
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this.fs.close(fd, () => {
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reject(err);
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});
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return;
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}
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currentBufferUsed += bytesRead;
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remaining -= bytesRead;
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if (currentBufferUsed === currentBuffer.length) {
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buf.push(currentBuffer);
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currentBuffer = undefined;
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if (remaining === 0) {
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this.fs.close(fd, err => {
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if (err) {
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reject(err);
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return;
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}
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resolve(buf);
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});
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return;
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}
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}
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read();
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}
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);
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};
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read();
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});
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});
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});
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return deserialize(this, false, readFile);
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}
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}
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module.exports = FileMiddleware;
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