1'use strict'
2
3const assert = require('assert')
4const Buffer = require('buffer').Buffer
5const realZlib = require('zlib')
6
7const constants = exports.constants = require('./constants.js')
8const Minipass = require('minipass')
9
10const OriginalBufferConcat = Buffer.concat
11
12const _superWrite = Symbol('_superWrite')
13class ZlibError extends Error {
14  constructor (err) {
15    super('zlib: ' + err.message)
16    this.code = err.code
17    this.errno = err.errno
18    /* istanbul ignore if */
19    if (!this.code)
20      this.code = 'ZLIB_ERROR'
21
22    this.message = 'zlib: ' + err.message
23    Error.captureStackTrace(this, this.constructor)
24  }
25
26  get name () {
27    return 'ZlibError'
28  }
29}
30
31// the Zlib class they all inherit from
32// This thing manages the queue of requests, and returns
33// true or false if there is anything in the queue when
34// you call the .write() method.
35const _opts = Symbol('opts')
36const _flushFlag = Symbol('flushFlag')
37const _finishFlushFlag = Symbol('finishFlushFlag')
38const _fullFlushFlag = Symbol('fullFlushFlag')
39const _handle = Symbol('handle')
40const _onError = Symbol('onError')
41const _sawError = Symbol('sawError')
42const _level = Symbol('level')
43const _strategy = Symbol('strategy')
44const _ended = Symbol('ended')
45const _defaultFullFlush = Symbol('_defaultFullFlush')
46
47class ZlibBase extends Minipass {
48  constructor (opts, mode) {
49    if (!opts || typeof opts !== 'object')
50      throw new TypeError('invalid options for ZlibBase constructor')
51
52    super(opts)
53    this[_sawError] = false
54    this[_ended] = false
55    this[_opts] = opts
56
57    this[_flushFlag] = opts.flush
58    this[_finishFlushFlag] = opts.finishFlush
59    // this will throw if any options are invalid for the class selected
60    try {
61      this[_handle] = new realZlib[mode](opts)
62    } catch (er) {
63      // make sure that all errors get decorated properly
64      throw new ZlibError(er)
65    }
66
67    this[_onError] = (err) => {
68      // no sense raising multiple errors, since we abort on the first one.
69      if (this[_sawError])
70        return
71
72      this[_sawError] = true
73
74      // there is no way to cleanly recover.
75      // continuing only obscures problems.
76      this.close()
77      this.emit('error', err)
78    }
79
80    this[_handle].on('error', er => this[_onError](new ZlibError(er)))
81    this.once('end', () => this.close)
82  }
83
84  close () {
85    if (this[_handle]) {
86      this[_handle].close()
87      this[_handle] = null
88      this.emit('close')
89    }
90  }
91
92  reset () {
93    if (!this[_sawError]) {
94      assert(this[_handle], 'zlib binding closed')
95      return this[_handle].reset()
96    }
97  }
98
99  flush (flushFlag) {
100    if (this.ended)
101      return
102
103    if (typeof flushFlag !== 'number')
104      flushFlag = this[_fullFlushFlag]
105    this.write(Object.assign(Buffer.alloc(0), { [_flushFlag]: flushFlag }))
106  }
107
108  end (chunk, encoding, cb) {
109    if (chunk)
110      this.write(chunk, encoding)
111    this.flush(this[_finishFlushFlag])
112    this[_ended] = true
113    return super.end(null, null, cb)
114  }
115
116  get ended () {
117    return this[_ended]
118  }
119
120  write (chunk, encoding, cb) {
121    // process the chunk using the sync process
122    // then super.write() all the outputted chunks
123    if (typeof encoding === 'function')
124      cb = encoding, encoding = 'utf8'
125
126    if (typeof chunk === 'string')
127      chunk = Buffer.from(chunk, encoding)
128
129    if (this[_sawError])
130      return
131    assert(this[_handle], 'zlib binding closed')
132
133    // _processChunk tries to .close() the native handle after it's done, so we
134    // intercept that by temporarily making it a no-op.
135    const nativeHandle = this[_handle]._handle
136    const originalNativeClose = nativeHandle.close
137    nativeHandle.close = () => {}
138    const originalClose = this[_handle].close
139    this[_handle].close = () => {}
140    // It also calls `Buffer.concat()` at the end, which may be convenient
141    // for some, but which we are not interested in as it slows us down.
142    Buffer.concat = (args) => args
143    let result
144    try {
145      const flushFlag = typeof chunk[_flushFlag] === 'number'
146        ? chunk[_flushFlag] : this[_flushFlag]
147      result = this[_handle]._processChunk(chunk, flushFlag)
148      // if we don't throw, reset it back how it was
149      Buffer.concat = OriginalBufferConcat
150    } catch (err) {
151      // or if we do, put Buffer.concat() back before we emit error
152      // Error events call into user code, which may call Buffer.concat()
153      Buffer.concat = OriginalBufferConcat
154      this[_onError](new ZlibError(err))
155    } finally {
156      if (this[_handle]) {
157        // Core zlib resets `_handle` to null after attempting to close the
158        // native handle. Our no-op handler prevented actual closure, but we
159        // need to restore the `._handle` property.
160        this[_handle]._handle = nativeHandle
161        nativeHandle.close = originalNativeClose
162        this[_handle].close = originalClose
163        // `_processChunk()` adds an 'error' listener. If we don't remove it
164        // after each call, these handlers start piling up.
165        this[_handle].removeAllListeners('error')
166        // make sure OUR error listener is still attached tho
167      }
168    }
169
170    if (this[_handle])
171      this[_handle].on('error', er => this[_onError](new ZlibError(er)))
172
173    let writeReturn
174    if (result) {
175      if (Array.isArray(result) && result.length > 0) {
176        // The first buffer is always `handle._outBuffer`, which would be
177        // re-used for later invocations; so, we always have to copy that one.
178        writeReturn = this[_superWrite](Buffer.from(result[0]))
179        for (let i = 1; i < result.length; i++) {
180          writeReturn = this[_superWrite](result[i])
181        }
182      } else {
183        writeReturn = this[_superWrite](Buffer.from(result))
184      }
185    }
186
187    if (cb)
188      cb()
189    return writeReturn
190  }
191
192  [_superWrite] (data) {
193    return super.write(data)
194  }
195}
196
197class Zlib extends ZlibBase {
198  constructor (opts, mode) {
199    opts = opts || {}
200
201    opts.flush = opts.flush || constants.Z_NO_FLUSH
202    opts.finishFlush = opts.finishFlush || constants.Z_FINISH
203    super(opts, mode)
204
205    this[_fullFlushFlag] = constants.Z_FULL_FLUSH
206    this[_level] = opts.level
207    this[_strategy] = opts.strategy
208  }
209
210  params (level, strategy) {
211    if (this[_sawError])
212      return
213
214    if (!this[_handle])
215      throw new Error('cannot switch params when binding is closed')
216
217    // no way to test this without also not supporting params at all
218    /* istanbul ignore if */
219    if (!this[_handle].params)
220      throw new Error('not supported in this implementation')
221
222    if (this[_level] !== level || this[_strategy] !== strategy) {
223      this.flush(constants.Z_SYNC_FLUSH)
224      assert(this[_handle], 'zlib binding closed')
225      // .params() calls .flush(), but the latter is always async in the
226      // core zlib. We override .flush() temporarily to intercept that and
227      // flush synchronously.
228      const origFlush = this[_handle].flush
229      this[_handle].flush = (flushFlag, cb) => {
230        this.flush(flushFlag)
231        cb()
232      }
233      try {
234        this[_handle].params(level, strategy)
235      } finally {
236        this[_handle].flush = origFlush
237      }
238      /* istanbul ignore else */
239      if (this[_handle]) {
240        this[_level] = level
241        this[_strategy] = strategy
242      }
243    }
244  }
245}
246
247// minimal 2-byte header
248class Deflate extends Zlib {
249  constructor (opts) {
250    super(opts, 'Deflate')
251  }
252}
253
254class Inflate extends Zlib {
255  constructor (opts) {
256    super(opts, 'Inflate')
257  }
258}
259
260// gzip - bigger header, same deflate compression
261const _portable = Symbol('_portable')
262class Gzip extends Zlib {
263  constructor (opts) {
264    super(opts, 'Gzip')
265    this[_portable] = opts && !!opts.portable
266  }
267
268  [_superWrite] (data) {
269    if (!this[_portable])
270      return super[_superWrite](data)
271
272    // we'll always get the header emitted in one first chunk
273    // overwrite the OS indicator byte with 0xFF
274    this[_portable] = false
275    data[9] = 255
276    return super[_superWrite](data)
277  }
278}
279
280class Gunzip extends Zlib {
281  constructor (opts) {
282    super(opts, 'Gunzip')
283  }
284}
285
286// raw - no header
287class DeflateRaw extends Zlib {
288  constructor (opts) {
289    super(opts, 'DeflateRaw')
290  }
291}
292
293class InflateRaw extends Zlib {
294  constructor (opts) {
295    super(opts, 'InflateRaw')
296  }
297}
298
299// auto-detect header.
300class Unzip extends Zlib {
301  constructor (opts) {
302    super(opts, 'Unzip')
303  }
304}
305
306class Brotli extends ZlibBase {
307  constructor (opts, mode) {
308    opts = opts || {}
309
310    opts.flush = opts.flush || constants.BROTLI_OPERATION_PROCESS
311    opts.finishFlush = opts.finishFlush || constants.BROTLI_OPERATION_FINISH
312
313    super(opts, mode)
314
315    this[_fullFlushFlag] = constants.BROTLI_OPERATION_FLUSH
316  }
317}
318
319class BrotliCompress extends Brotli {
320  constructor (opts) {
321    super(opts, 'BrotliCompress')
322  }
323}
324
325class BrotliDecompress extends Brotli {
326  constructor (opts) {
327    super(opts, 'BrotliDecompress')
328  }
329}
330
331exports.Deflate = Deflate
332exports.Inflate = Inflate
333exports.Gzip = Gzip
334exports.Gunzip = Gunzip
335exports.DeflateRaw = DeflateRaw
336exports.InflateRaw = InflateRaw
337exports.Unzip = Unzip
338/* istanbul ignore else */
339if (typeof realZlib.BrotliCompress === 'function') {
340  exports.BrotliCompress = BrotliCompress
341  exports.BrotliDecompress = BrotliDecompress
342} else {
343  exports.BrotliCompress = exports.BrotliDecompress = class {
344    constructor () {
345      throw new Error('Brotli is not supported in this version of Node.js')
346    }
347  }
348}
349