gzip/lib/inflate.js

import zlib_inflate from './zlib/inflate.js'
import { flattenChunks } from './utils/common.js'
import { string2buf, utf8border, buf2string } from './utils/strings.js'
import msg from './zlib/messages.js'
import ZStream from './zlib/zstream.js'
import GZheader from './zlib/gzheader.js'

const toString = Object.prototype.toString

/* Public constants ==========================================================*/
/* ===========================================================================*/

import {
  Z_NO_FLUSH,
  Z_FINISH,
  Z_OK,
  Z_STREAM_END,
  Z_NEED_DICT,
  Z_STREAM_ERROR,
  Z_DATA_ERROR,
  Z_MEM_ERROR
} from './zlib/constants.js'

/* ===========================================================================*/

/**
 * class Inflate
 *
 * Generic JS-style wrapper for zlib calls. If you don't need
 * streaming behaviour - use more simple functions: [[inflate]]
 * and [[inflateRaw]].
 **/

/* internal
 * inflate.chunks -> Array
 *
 * Chunks of output data, if [[Inflate#onData]] not overridden.
 **/

/**
 * Inflate.result -> Uint8Array|String
 *
 * Uncompressed result, generated by default [[Inflate#onData]]
 * and [[Inflate#onEnd]] handlers. Filled after you push last chunk
 * (call [[Inflate#push]] with `Z_FINISH` / `true` param).
 **/

/**
 * Inflate.err -> Number
 *
 * Error code after inflate finished. 0 (Z_OK) on success.
 * Should be checked if broken data possible.
 **/

/**
 * Inflate.msg -> String
 *
 * Error message, if [[Inflate.err]] != 0
 **/

/**
 * new Inflate(options)
 * - options (Object): zlib inflate options.
 *
 * Creates new inflator instance with specified params. Throws exception
 * on bad params. Supported options:
 *
 * - `windowBits`
 * - `dictionary`
 *
 * [http://zlib.net/manual.html#Advanced](http://zlib.net/manual.html#Advanced)
 * for more information on these.
 *
 * Additional options, for internal needs:
 *
 * - `chunkSize` - size of generated data chunks (16K by default)
 * - `raw` (Boolean) - do raw inflate
 * - `to` (String) - if equal to 'string', then result will be converted
 *   from utf8 to utf16 (javascript) string. When string output requested,
 *   chunk length can differ from `chunkSize`, depending on content.
 *
 * By default, when no options set, autodetect deflate/gzip data format via
 * wrapper header.
 *
 * ##### Example:
 *
 * ```javascript
 * const pako from 'pako')
 * const chunk1 = new Uint8Array([1,2,3,4,5,6,7,8,9])
 * const chunk2 = new Uint8Array([10,11,12,13,14,15,16,17,18,19]);
 *
 * const inflate = new pako.Inflate({ level: 3});
 *
 * inflate.push(chunk1, false);
 * inflate.push(chunk2, true);  // true -> last chunk
 *
 * if (inflate.err) { throw new Error(inflate.err); }
 *
 * console.log(inflate.result);
 * ```
 **/
function Inflate(options) {
  this.options = Object.assign(
    {
      chunkSize: 1024 * 64,
      windowBits: 15,
      to: ''
    },
    options || {}
  )

  const opt = this.options

  // Force window size for `raw` data, if not set directly,
  // because we have no header for autodetect.
  if (opt.raw && opt.windowBits >= 0 && opt.windowBits < 16) {
    opt.windowBits = -opt.windowBits
    if (opt.windowBits === 0) {
      opt.windowBits = -15
    }
  }

  // If `windowBits` not defined (and mode not raw) - set autodetect flag for gzip/deflate
  if (
    opt.windowBits >= 0 &&
    opt.windowBits < 16 &&
    !(options && options.windowBits)
  ) {
    opt.windowBits += 32
  }

  // Gzip header has no info about windows size, we can do autodetect only
  // for deflate. So, if window size not set, force it to max when gzip possible
  if (opt.windowBits > 15 && opt.windowBits < 48) {
    // bit 3 (16) -> gzipped data
    // bit 4 (32) -> autodetect gzip/deflate
    if ((opt.windowBits & 15) === 0) {
      opt.windowBits |= 15
    }
  }

  this.err = 0 // error code, if happens (0 = Z_OK)
  this.msg = '' // error message
  this.ended = false // used to avoid multiple onEnd() calls
  this.chunks = [] // chunks of compressed data

  this.strm = new ZStream()
  this.strm.avail_out = 0

  let status = zlib_inflate.inflateInit2(this.strm, opt.windowBits)

  if (status !== Z_OK) {
    throw new Error(msg[status])
  }

  this.header = new GZheader()

  zlib_inflate.inflateGetHeader(this.strm, this.header)

  // Setup dictionary
  if (opt.dictionary) {
    // Convert data if needed
    if (typeof opt.dictionary === 'string') {
      opt.dictionary = string2buf(opt.dictionary)
    } else if (toString.call(opt.dictionary) === '[object ArrayBuffer]') {
      opt.dictionary = new Uint8Array(opt.dictionary)
    }
    if (opt.raw) {
      //In raw mode we need to set the dictionary early
      status = zlib_inflate.inflateSetDictionary(this.strm, opt.dictionary)
      if (status !== Z_OK) {
        throw new Error(msg[status])
      }
    }
  }
}

/**
 * Inflate#push(data[, flush_mode]) -> Boolean
 * - data (Uint8Array|ArrayBuffer): input data
 * - flush_mode (Number|Boolean): 0..6 for corresponding Z_NO_FLUSH..Z_TREE
 *   flush modes. See constants. Skipped or `false` means Z_NO_FLUSH,
 *   `true` means Z_FINISH.
 *
 * Sends input data to inflate pipe, generating [[Inflate#onData]] calls with
 * new output chunks. Returns `true` on success. If end of stream detected,
 * [[Inflate#onEnd]] will be called.
 *
 * `flush_mode` is not needed for normal operation, because end of stream
 * detected automatically. You may try to use it for advanced things, but
 * this functionality was not tested.
 *
 * On fail call [[Inflate#onEnd]] with error code and return false.
 *
 * ##### Example
 *
 * ```javascript
 * push(chunk, false); // push one of data chunks
 * ...
 * push(chunk, true);  // push last chunk
 * ```
 **/
Inflate.prototype.push = function (data, flush_mode) {
  const strm = this.strm
  const chunkSize = this.options.chunkSize
  const dictionary = this.options.dictionary
  let status, _flush_mode, last_avail_out

  if (this.ended) return false

  if (flush_mode === ~~flush_mode) _flush_mode = flush_mode
  else _flush_mode = flush_mode === true ? Z_FINISH : Z_NO_FLUSH

  // Convert data if needed
  if (toString.call(data) === '[object ArrayBuffer]') {
    strm.input = new Uint8Array(data)
  } else {
    strm.input = data
  }

  strm.next_in = 0
  strm.avail_in = strm.input.length

  for (;;) {
    if (strm.avail_out === 0) {
      strm.output = new Uint8Array(chunkSize)
      strm.next_out = 0
      strm.avail_out = chunkSize
    }

    status = zlib_inflate.inflate(strm, _flush_mode)

    if (status === Z_NEED_DICT && dictionary) {
      status = zlib_inflate.inflateSetDictionary(strm, dictionary)

      if (status === Z_OK) {
        status = zlib_inflate.inflate(strm, _flush_mode)
      } else if (status === Z_DATA_ERROR) {
        // Replace code with more verbose
        status = Z_NEED_DICT
      }
    }

    // Skip snyc markers if more data follows and not raw mode
    while (
      strm.avail_in > 0 &&
      status === Z_STREAM_END &&
      strm.state.wrap > 0 &&
      data[strm.next_in] !== 0
    ) {
      zlib_inflate.inflateReset(strm)
      status = zlib_inflate.inflate(strm, _flush_mode)
    }

    switch (status) {
      case Z_STREAM_ERROR:
      case Z_DATA_ERROR:
      case Z_NEED_DICT:
      case Z_MEM_ERROR:
        this.onEnd(status)
        this.ended = true
        return false
    }

    // Remember real `avail_out` value, because we may patch out buffer content
    // to align utf8 strings boundaries.
    last_avail_out = strm.avail_out

    if (strm.next_out) {
      if (strm.avail_out === 0 || status === Z_STREAM_END) {
        if (this.options.to === 'string') {
          let next_out_utf8 = utf8border(strm.output, strm.next_out)

          let tail = strm.next_out - next_out_utf8
          let utf8str = buf2string(strm.output, next_out_utf8)

          // move tail & realign counters
          strm.next_out = tail
          strm.avail_out = chunkSize - tail
          if (tail)
            strm.output.set(
              strm.output.subarray(next_out_utf8, next_out_utf8 + tail),
              0
            )

          this.onData(utf8str)
        } else {
          this.onData(
            strm.output.length === strm.next_out
              ? strm.output
              : strm.output.subarray(0, strm.next_out)
          )
        }
      }
    }

    // Must repeat iteration if out buffer is full
    if (status === Z_OK && last_avail_out === 0) continue

    // Finalize if end of stream reached.
    if (status === Z_STREAM_END) {
      status = zlib_inflate.inflateEnd(this.strm)
      this.onEnd(status)
      this.ended = true
      return true
    }

    if (strm.avail_in === 0) break
  }

  return true
}

/**
 * Inflate#onData(chunk) -> Void
 * - chunk (Uint8Array|String): output data. When string output requested,
 *   each chunk will be string.
 *
 * By default, stores data blocks in `chunks[]` property and glue
 * those in `onEnd`. Override this handler, if you need another behaviour.
 **/
Inflate.prototype.onData = function (chunk) {
  this.chunks.push(chunk)
}

/**
 * Inflate#onEnd(status) -> Void
 * - status (Number): inflate status. 0 (Z_OK) on success,
 *   other if not.
 *
 * Called either after you tell inflate that the input stream is
 * complete (Z_FINISH). By default - join collected chunks,
 * free memory and fill `results` / `err` properties.
 **/
Inflate.prototype.onEnd = function (status) {
  // On success - join
  if (status === Z_OK) {
    if (this.options.to === 'string') {
      this.result = this.chunks.join('')
    } else {
      this.result = flattenChunks(this.chunks)
    }
  }
  this.chunks = []
  this.err = status
  this.msg = this.strm.msg
}

/**
 * inflate(data[, options]) -> Uint8Array|String
 * - data (Uint8Array|ArrayBuffer): input data to decompress.
 * - options (Object): zlib inflate options.
 *
 * Decompress `data` with inflate/ungzip and `options`. Autodetect
 * format via wrapper header by default. That's why we don't provide
 * separate `ungzip` method.
 *
 * Supported options are:
 *
 * - windowBits
 *
 * [http://zlib.net/manual.html#Advanced](http://zlib.net/manual.html#Advanced)
 * for more information.
 *
 * Sugar (options):
 *
 * - `raw` (Boolean) - say that we work with raw stream, if you don't wish to specify
 *   negative windowBits implicitly.
 * - `to` (String) - if equal to 'string', then result will be converted
 *   from utf8 to utf16 (javascript) string. When string output requested,
 *   chunk length can differ from `chunkSize`, depending on content.
 *
 *
 * ##### Example:
 *
 * ```javascript
 * const pako from 'pako');
 * const input = pako.deflate(new Uint8Array([1,2,3,4,5,6,7,8,9]));
 * let output;
 *
 * try {
 *   output = pako.inflate(input);
 * } catch (err) {
 *   console.log(err);
 * }
 * ```
 **/
function ungzip(input, options) {
  const inflator = new Inflate(options)

  inflator.push(input)

  // That will never happens, if you don't cheat with options :)
  if (inflator.err) throw inflator.msg || msg[inflator.err]

  return inflator.result
}

/**
 * ungzip(data[, options]) -> Uint8Array|String
 * - data (Uint8Array|ArrayBuffer): input data to decompress.
 * - options (Object): zlib inflate options.
 *
 * Just shortcut to [[inflate]], because it autodetects format
 * by header.content. Done for convenience.
 **/

export { ungzip }