Add deflator helper class for deflating data

Wraps pako's deflate for easier usage.
This commit is contained in:
Niko Lehto 2020-02-07 13:23:21 +01:00 committed by Lauri Kasanen
parent 24cf1f0f9a
commit fdeefcfab4
3 changed files with 189 additions and 30 deletions

79
kasmweb/core/deflator.js Normal file
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@ -0,0 +1,79 @@
/*
* noVNC: HTML5 VNC client
* Copyright (C) 2020 The noVNC Authors
* Licensed under MPL 2.0 (see LICENSE.txt)
*
* See README.md for usage and integration instructions.
*/
import { deflateInit, deflate } from "../vendor/pako/lib/zlib/deflate.js";
import { Z_FULL_FLUSH } from "../vendor/pako/lib/zlib/deflate.js";
import ZStream from "../vendor/pako/lib/zlib/zstream.js";
export default class Deflator {
constructor() {
this.strm = new ZStream();
this.chunkSize = 1024 * 10 * 10;
this.outputBuffer = new Uint8Array(this.chunkSize);
this.windowBits = 5;
deflateInit(this.strm, this.windowBits);
}
deflate(inData) {
this.strm.input = inData;
this.strm.avail_in = this.strm.input.length;
this.strm.next_in = 0;
this.strm.output = this.outputBuffer;
this.strm.avail_out = this.chunkSize;
this.strm.next_out = 0;
let lastRet = deflate(this.strm, Z_FULL_FLUSH);
let outData = new Uint8Array(this.strm.output.buffer, 0, this.strm.next_out);
if (lastRet < 0) {
throw new Error("zlib deflate failed");
}
if (this.strm.avail_in > 0) {
// Read chunks until done
let chunks = [outData];
let totalLen = outData.length;
do {
this.strm.output = new Uint8Array(this.chunkSize);
this.strm.next_out = 0;
this.strm.avail_out = this.chunkSize;
lastRet = deflate(this.strm, Z_FULL_FLUSH);
if (lastRet < 0) {
throw new Error("zlib deflate failed");
}
let chunk = new Uint8Array(this.strm.output.buffer, 0, this.strm.next_out);
totalLen += chunk.length;
chunks.push(chunk);
} while (this.strm.avail_in > 0);
// Combine chunks into a single data
let newData = new Uint8Array(totalLen);
let offset = 0;
for (let i = 0; i < chunks.length; i++) {
newData.set(chunks[i], offset);
offset += chunks[i].length;
}
outData = newData;
}
this.strm.input = null;
this.strm.avail_in = 0;
this.strm.next_in = 0;
return outData;
}
}

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@ -0,0 +1,80 @@
/* eslint-disable no-console */
const expect = chai.expect;
import { inflateInit, inflate } from "../vendor/pako/lib/zlib/inflate.js";
import ZStream from "../vendor/pako/lib/zlib/zstream.js";
import Deflator from "../core/deflator.js";
function _inflator(compText, expected) {
let strm = new ZStream();
let chunkSize = 1024 * 10 * 10;
strm.output = new Uint8Array(chunkSize);
inflateInit(strm, 5);
if (expected > chunkSize) {
chunkSize = expected;
strm.output = new Uint8Array(chunkSize);
}
strm.input = compText;
strm.avail_in = strm.input.length;
strm.next_in = 0;
strm.next_out = 0;
strm.avail_out = expected.length;
let ret = inflate(strm, 0);
// Check that return code is not an error
expect(ret).to.be.greaterThan(-1);
return new Uint8Array(strm.output.buffer, 0, strm.next_out);
}
describe('Deflate data', function () {
it('should be able to deflate messages', function () {
let deflator = new Deflator();
let text = "123asdf";
let preText = new Uint8Array(text.length);
for (let i = 0; i < preText.length; i++) {
preText[i] = text.charCodeAt(i);
}
let compText = deflator.deflate(preText);
let inflatedText = _inflator(compText, text.length);
expect(inflatedText).to.array.equal(preText);
});
it('should be able to deflate large messages', function () {
let deflator = new Deflator();
/* Generate a big string with random characters. Used because
repetition of letters might be deflated more effectively than
random ones. */
let text = "";
let characters = 'ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789';
for (let i = 0; i < 300000; i++) {
text += characters.charAt(Math.floor(Math.random() * characters.length));
}
let preText = new Uint8Array(text.length);
for (let i = 0; i < preText.length; i++) {
preText[i] = text.charCodeAt(i);
}
let compText = deflator.deflate(preText);
//Check that the compressed size is expected size
expect(compText.length).to.be.greaterThan((1024 * 10 * 10) * 2);
let inflatedText = _inflator(compText, text.length);
expect(inflatedText).to.array.equal(preText);
});
});

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@ -9,51 +9,51 @@ import msg from "./messages.js";
/* Allowed flush values; see deflate() and inflate() below for details */
var Z_NO_FLUSH = 0;
var Z_PARTIAL_FLUSH = 1;
//var Z_SYNC_FLUSH = 2;
var Z_FULL_FLUSH = 3;
var Z_FINISH = 4;
var Z_BLOCK = 5;
//var Z_TREES = 6;
export const Z_NO_FLUSH = 0;
export const Z_PARTIAL_FLUSH = 1;
//export const Z_SYNC_FLUSH = 2;
export const Z_FULL_FLUSH = 3;
export const Z_FINISH = 4;
export const Z_BLOCK = 5;
//export const Z_TREES = 6;
/* Return codes for the compression/decompression functions. Negative values
* are errors, positive values are used for special but normal events.
*/
var Z_OK = 0;
var Z_STREAM_END = 1;
//var Z_NEED_DICT = 2;
//var Z_ERRNO = -1;
var Z_STREAM_ERROR = -2;
var Z_DATA_ERROR = -3;
//var Z_MEM_ERROR = -4;
var Z_BUF_ERROR = -5;
//var Z_VERSION_ERROR = -6;
export const Z_OK = 0;
export const Z_STREAM_END = 1;
//export const Z_NEED_DICT = 2;
//export const Z_ERRNO = -1;
export const Z_STREAM_ERROR = -2;
export const Z_DATA_ERROR = -3;
//export const Z_MEM_ERROR = -4;
export const Z_BUF_ERROR = -5;
//export const Z_VERSION_ERROR = -6;
/* compression levels */
//var Z_NO_COMPRESSION = 0;
//var Z_BEST_SPEED = 1;
//var Z_BEST_COMPRESSION = 9;
var Z_DEFAULT_COMPRESSION = -1;
//export const Z_NO_COMPRESSION = 0;
//export const Z_BEST_SPEED = 1;
//export const Z_BEST_COMPRESSION = 9;
export const Z_DEFAULT_COMPRESSION = -1;
var Z_FILTERED = 1;
var Z_HUFFMAN_ONLY = 2;
var Z_RLE = 3;
var Z_FIXED = 4;
var Z_DEFAULT_STRATEGY = 0;
export const Z_FILTERED = 1;
export const Z_HUFFMAN_ONLY = 2;
export const Z_RLE = 3;
export const Z_FIXED = 4;
export const Z_DEFAULT_STRATEGY = 0;
/* Possible values of the data_type field (though see inflate()) */
//var Z_BINARY = 0;
//var Z_TEXT = 1;
//var Z_ASCII = 1; // = Z_TEXT
var Z_UNKNOWN = 2;
//export const Z_BINARY = 0;
//export const Z_TEXT = 1;
//export const Z_ASCII = 1; // = Z_TEXT
export const Z_UNKNOWN = 2;
/* The deflate compression method */
var Z_DEFLATED = 8;
export const Z_DEFLATED = 8;
/*============================================================================*/