webpack/lib/util/hash/wasm-hash.js

Packs CommonJs/AMD modules for the browser. Allows to split your codebase into multiple bundles, which can be loaded on demand. Support loaders to preprocess files, i.e. json, jsx, es7, css, less, ... and your custom stuff.

/*
	MIT License http://www.opensource.org/licenses/mit-license.php
	Author Tobias Koppers @sokra
*/

"use strict";

// 65536 is the size of a wasm memory page
// 64 is the maximum chunk size for every possible wasm hash implementation
// 4 is the maximum number of bytes per char for string encoding (max is utf-8)
// ~3 makes sure that it's always a block of 4 chars, so avoid partially encoded bytes for base64
const MAX_SHORT_STRING = Math.floor((65536 - 64) / 4) & ~3;

class WasmHash {
	/**
	 * @param {WebAssembly.Instance} instance wasm instance
	 * @param {WebAssembly.Instance[]} instancesPool pool of instances
	 * @param {number} chunkSize size of data chunks passed to wasm
	 * @param {number} digestSize size of digest returned by wasm
	 */
	constructor(instance, instancesPool, chunkSize, digestSize) {
		const exports = /** @type {any} */ (instance.exports);
		exports.init();
		this.exports = exports;
		this.mem = Buffer.from(exports.memory.buffer, 0, 65536);
		this.buffered = 0;
		this.instancesPool = instancesPool;
		this.chunkSize = chunkSize;
		this.digestSize = digestSize;
	}

	reset() {
		this.buffered = 0;
		this.exports.init();
	}

	/**
	 * @param {Buffer | string} data data
	 * @param {BufferEncoding=} encoding encoding
	 * @returns {this} itself
	 */
	update(data, encoding) {
		if (typeof data === "string") {
			while (data.length > MAX_SHORT_STRING) {
				this._updateWithShortString(data.slice(0, MAX_SHORT_STRING), encoding);
				data = data.slice(MAX_SHORT_STRING);
			}
			this._updateWithShortString(data, encoding);
			return this;
		}
		this._updateWithBuffer(data);
		return this;
	}

	/**
	 * @param {string} data data
	 * @param {BufferEncoding=} encoding encoding
	 * @returns {void}
	 */
	_updateWithShortString(data, encoding) {
		const { exports, buffered, mem, chunkSize } = this;
		let endPos;
		if (data.length < 70) {
			if (!encoding || encoding === "utf-8" || encoding === "utf8") {
				endPos = buffered;
				for (let i = 0; i < data.length; i++) {
					const cc = data.charCodeAt(i);
					if (cc < 0x80) mem[endPos++] = cc;
					else if (cc < 0x800) {
						mem[endPos] = (cc >> 6) | 0xc0;
						mem[endPos + 1] = (cc & 0x3f) | 0x80;
						endPos += 2;
					} else {
						// bail-out for weird chars
						endPos += mem.write(data.slice(i), endPos, encoding);
						break;
					}
				}
			} else if (encoding === "latin1") {
				endPos = buffered;
				for (let i = 0; i < data.length; i++) {
					const cc = data.charCodeAt(i);
					mem[endPos++] = cc;
				}
			} else {
				endPos = buffered + mem.write(data, buffered, encoding);
			}
		} else {
			endPos = buffered + mem.write(data, buffered, encoding);
		}
		if (endPos < chunkSize) {
			this.buffered = endPos;
		} else {
			const l = endPos & ~(this.chunkSize - 1);
			exports.update(l);
			const newBuffered = endPos - l;
			this.buffered = newBuffered;
			if (newBuffered > 0) mem.copyWithin(0, l, endPos);
		}
	}

	/**
	 * @param {Buffer} data data
	 * @returns {void}
	 */
	_updateWithBuffer(data) {
		const { exports, buffered, mem } = this;
		const length = data.length;
		if (buffered + length < this.chunkSize) {
			data.copy(mem, buffered, 0, length);
			this.buffered += length;
		} else {
			const l = (buffered + length) & ~(this.chunkSize - 1);
			if (l > 65536) {
				let i = 65536 - buffered;
				data.copy(mem, buffered, 0, i);
				exports.update(65536);
				const stop = l - buffered - 65536;
				while (i < stop) {
					data.copy(mem, 0, i, i + 65536);
					exports.update(65536);
					i += 65536;
				}
				data.copy(mem, 0, i, l - buffered);
				exports.update(l - buffered - i);
			} else {
				data.copy(mem, buffered, 0, l - buffered);
				exports.update(l);
			}
			const newBuffered = length + buffered - l;
			this.buffered = newBuffered;
			if (newBuffered > 0) data.copy(mem, 0, length - newBuffered, length);
		}
	}

	digest(type) {
		const { exports, buffered, mem, digestSize } = this;
		exports.final(buffered);
		this.instancesPool.push(this);
		const hex = mem.toString("latin1", 0, digestSize);
		if (type === "hex") return hex;
		if (type === "binary" || !type) return Buffer.from(hex, "hex");
		return Buffer.from(hex, "hex").toString(type);
	}
}

const create = (wasmModule, instancesPool, chunkSize, digestSize) => {
	if (instancesPool.length > 0) {
		const old = instancesPool.pop();
		old.reset();
		return old;
	} else {
		return new WasmHash(
			new WebAssembly.Instance(wasmModule),
			instancesPool,
			chunkSize,
			digestSize
		);
	}
};

module.exports = create;
module.exports.MAX_SHORT_STRING = MAX_SHORT_STRING;