381 lines
9.9 KiB
JavaScript
381 lines
9.9 KiB
JavaScript
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'use strict';
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const zlib_deflate = require('./zlib/deflate');
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const utils = require('./utils/common');
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const strings = require('./utils/strings');
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const msg = require('./zlib/messages');
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const ZStream = require('./zlib/zstream');
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const toString = Object.prototype.toString;
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/* Public constants ==========================================================*/
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/* ===========================================================================*/
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const {
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Z_NO_FLUSH, Z_SYNC_FLUSH, Z_FULL_FLUSH, Z_FINISH,
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Z_OK, Z_STREAM_END,
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Z_DEFAULT_COMPRESSION,
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Z_DEFAULT_STRATEGY,
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Z_DEFLATED
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} = require('./zlib/constants');
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/* ===========================================================================*/
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/**
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* class Deflate
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*
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* Generic JS-style wrapper for zlib calls. If you don't need
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* streaming behaviour - use more simple functions: [[deflate]],
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* [[deflateRaw]] and [[gzip]].
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**/
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/* internal
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* Deflate.chunks -> Array
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*
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* Chunks of output data, if [[Deflate#onData]] not overridden.
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**/
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/**
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* Deflate.result -> Uint8Array
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*
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* Compressed result, generated by default [[Deflate#onData]]
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* and [[Deflate#onEnd]] handlers. Filled after you push last chunk
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* (call [[Deflate#push]] with `Z_FINISH` / `true` param).
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**/
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/**
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* Deflate.err -> Number
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*
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* Error code after deflate finished. 0 (Z_OK) on success.
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* You will not need it in real life, because deflate errors
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* are possible only on wrong options or bad `onData` / `onEnd`
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* custom handlers.
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**/
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/**
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* Deflate.msg -> String
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*
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* Error message, if [[Deflate.err]] != 0
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**/
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/**
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* new Deflate(options)
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* - options (Object): zlib deflate options.
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*
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* Creates new deflator instance with specified params. Throws exception
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* on bad params. Supported options:
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*
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* - `level`
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* - `windowBits`
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* - `memLevel`
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* - `strategy`
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* - `dictionary`
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*
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* [http://zlib.net/manual.html#Advanced](http://zlib.net/manual.html#Advanced)
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* for more information on these.
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*
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* Additional options, for internal needs:
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*
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* - `chunkSize` - size of generated data chunks (16K by default)
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* - `raw` (Boolean) - do raw deflate
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* - `gzip` (Boolean) - create gzip wrapper
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* - `header` (Object) - custom header for gzip
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* - `text` (Boolean) - true if compressed data believed to be text
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* - `time` (Number) - modification time, unix timestamp
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* - `os` (Number) - operation system code
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* - `extra` (Array) - array of bytes with extra data (max 65536)
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* - `name` (String) - file name (binary string)
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* - `comment` (String) - comment (binary string)
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* - `hcrc` (Boolean) - true if header crc should be added
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*
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* ##### Example:
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*
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* ```javascript
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* const pako = require('pako')
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* , chunk1 = new Uint8Array([1,2,3,4,5,6,7,8,9])
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* , chunk2 = new Uint8Array([10,11,12,13,14,15,16,17,18,19]);
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*
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* const deflate = new pako.Deflate({ level: 3});
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*
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* deflate.push(chunk1, false);
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* deflate.push(chunk2, true); // true -> last chunk
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*
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* if (deflate.err) { throw new Error(deflate.err); }
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*
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* console.log(deflate.result);
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* ```
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**/
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function Deflate(options) {
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this.options = utils.assign({
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level: Z_DEFAULT_COMPRESSION,
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method: Z_DEFLATED,
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chunkSize: 16384,
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windowBits: 15,
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memLevel: 8,
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strategy: Z_DEFAULT_STRATEGY
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}, options || {});
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let opt = this.options;
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if (opt.raw && (opt.windowBits > 0)) {
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opt.windowBits = -opt.windowBits;
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}
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else if (opt.gzip && (opt.windowBits > 0) && (opt.windowBits < 16)) {
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opt.windowBits += 16;
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}
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this.err = 0; // error code, if happens (0 = Z_OK)
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this.msg = ''; // error message
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this.ended = false; // used to avoid multiple onEnd() calls
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this.chunks = []; // chunks of compressed data
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this.strm = new ZStream();
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this.strm.avail_out = 0;
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let status = zlib_deflate.deflateInit2(
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this.strm,
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opt.level,
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opt.method,
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opt.windowBits,
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opt.memLevel,
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opt.strategy
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);
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if (status !== Z_OK) {
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throw new Error(msg[status]);
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}
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if (opt.header) {
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zlib_deflate.deflateSetHeader(this.strm, opt.header);
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}
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if (opt.dictionary) {
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let dict;
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// Convert data if needed
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if (typeof opt.dictionary === 'string') {
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// If we need to compress text, change encoding to utf8.
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dict = strings.string2buf(opt.dictionary);
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} else if (toString.call(opt.dictionary) === '[object ArrayBuffer]') {
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dict = new Uint8Array(opt.dictionary);
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} else {
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dict = opt.dictionary;
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}
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status = zlib_deflate.deflateSetDictionary(this.strm, dict);
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if (status !== Z_OK) {
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throw new Error(msg[status]);
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}
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this._dict_set = true;
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}
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}
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/**
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* Deflate#push(data[, flush_mode]) -> Boolean
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* - data (Uint8Array|ArrayBuffer|String): input data. Strings will be
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* converted to utf8 byte sequence.
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* - flush_mode (Number|Boolean): 0..6 for corresponding Z_NO_FLUSH..Z_TREE modes.
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* See constants. Skipped or `false` means Z_NO_FLUSH, `true` means Z_FINISH.
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*
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* Sends input data to deflate pipe, generating [[Deflate#onData]] calls with
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* new compressed chunks. Returns `true` on success. The last data block must
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* have `flush_mode` Z_FINISH (or `true`). That will flush internal pending
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* buffers and call [[Deflate#onEnd]].
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*
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* On fail call [[Deflate#onEnd]] with error code and return false.
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*
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* ##### Example
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*
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* ```javascript
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* push(chunk, false); // push one of data chunks
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* ...
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* push(chunk, true); // push last chunk
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* ```
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**/
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Deflate.prototype.push = function (data, flush_mode) {
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const strm = this.strm;
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const chunkSize = this.options.chunkSize;
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let status, _flush_mode;
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if (this.ended) { return false; }
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if (flush_mode === ~~flush_mode) _flush_mode = flush_mode;
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else _flush_mode = flush_mode === true ? Z_FINISH : Z_NO_FLUSH;
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// Convert data if needed
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if (typeof data === 'string') {
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// If we need to compress text, change encoding to utf8.
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strm.input = strings.string2buf(data);
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} else if (toString.call(data) === '[object ArrayBuffer]') {
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strm.input = new Uint8Array(data);
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} else {
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strm.input = data;
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}
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strm.next_in = 0;
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strm.avail_in = strm.input.length;
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for (;;) {
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if (strm.avail_out === 0) {
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strm.output = new Uint8Array(chunkSize);
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strm.next_out = 0;
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strm.avail_out = chunkSize;
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}
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// Make sure avail_out > 6 to avoid repeating markers
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if ((_flush_mode === Z_SYNC_FLUSH || _flush_mode === Z_FULL_FLUSH) && strm.avail_out <= 6) {
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this.onData(strm.output.subarray(0, strm.next_out));
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strm.avail_out = 0;
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continue;
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}
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status = zlib_deflate.deflate(strm, _flush_mode);
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// Ended => flush and finish
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if (status === Z_STREAM_END) {
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if (strm.next_out > 0) {
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this.onData(strm.output.subarray(0, strm.next_out));
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}
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status = zlib_deflate.deflateEnd(this.strm);
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this.onEnd(status);
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this.ended = true;
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return status === Z_OK;
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}
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// Flush if out buffer full
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if (strm.avail_out === 0) {
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this.onData(strm.output);
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continue;
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}
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// Flush if requested and has data
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if (_flush_mode > 0 && strm.next_out > 0) {
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this.onData(strm.output.subarray(0, strm.next_out));
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strm.avail_out = 0;
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continue;
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}
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if (strm.avail_in === 0) break;
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}
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return true;
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};
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/**
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* Deflate#onData(chunk) -> Void
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* - chunk (Uint8Array): output data.
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*
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* By default, stores data blocks in `chunks[]` property and glue
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* those in `onEnd`. Override this handler, if you need another behaviour.
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**/
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Deflate.prototype.onData = function (chunk) {
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this.chunks.push(chunk);
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};
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/**
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* Deflate#onEnd(status) -> Void
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* - status (Number): deflate status. 0 (Z_OK) on success,
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* other if not.
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*
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* Called once after you tell deflate that the input stream is
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* complete (Z_FINISH). By default - join collected chunks,
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* free memory and fill `results` / `err` properties.
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**/
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Deflate.prototype.onEnd = function (status) {
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// On success - join
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if (status === Z_OK) {
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this.result = utils.flattenChunks(this.chunks);
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}
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this.chunks = [];
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this.err = status;
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this.msg = this.strm.msg;
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};
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/**
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* deflate(data[, options]) -> Uint8Array
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* - data (Uint8Array|ArrayBuffer|String): input data to compress.
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* - options (Object): zlib deflate options.
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*
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* Compress `data` with deflate algorithm and `options`.
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*
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* Supported options are:
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*
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* - level
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* - windowBits
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* - memLevel
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* - strategy
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* - dictionary
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*
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* [http://zlib.net/manual.html#Advanced](http://zlib.net/manual.html#Advanced)
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* for more information on these.
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*
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* Sugar (options):
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*
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* - `raw` (Boolean) - say that we work with raw stream, if you don't wish to specify
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* negative windowBits implicitly.
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*
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* ##### Example:
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*
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* ```javascript
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* const pako = require('pako')
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* const data = new Uint8Array([1,2,3,4,5,6,7,8,9]);
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*
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* console.log(pako.deflate(data));
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* ```
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**/
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function deflate(input, options) {
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const deflator = new Deflate(options);
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deflator.push(input, true);
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// That will never happens, if you don't cheat with options :)
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if (deflator.err) { throw deflator.msg || msg[deflator.err]; }
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return deflator.result;
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}
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/**
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* deflateRaw(data[, options]) -> Uint8Array
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* - data (Uint8Array|ArrayBuffer|String): input data to compress.
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* - options (Object): zlib deflate options.
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*
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* The same as [[deflate]], but creates raw data, without wrapper
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* (header and adler32 crc).
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**/
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function deflateRaw(input, options) {
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options = options || {};
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options.raw = true;
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return deflate(input, options);
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}
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/**
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* gzip(data[, options]) -> Uint8Array
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* - data (Uint8Array|ArrayBuffer|String): input data to compress.
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* - options (Object): zlib deflate options.
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*
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* The same as [[deflate]], but create gzip wrapper instead of
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* deflate one.
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**/
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function gzip(input, options) {
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options = options || {};
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options.gzip = true;
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return deflate(input, options);
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}
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module.exports.Deflate = Deflate;
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module.exports.deflate = deflate;
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module.exports.deflateRaw = deflateRaw;
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module.exports.gzip = gzip;
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module.exports.constants = require('./zlib/constants');
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