readmongo/node_modules/browserify-zlib/lib/binding.js

'use strict';
/* eslint camelcase: "off" */

var assert = require('assert');

var Zstream = require('pako/lib/zlib/zstream');
var zlib_deflate = require('pako/lib/zlib/deflate.js');
var zlib_inflate = require('pako/lib/zlib/inflate.js');
var constants = require('pako/lib/zlib/constants');

for (var key in constants) {
  exports[key] = constants[key];
}

// zlib modes
exports.NONE = 0;
exports.DEFLATE = 1;
exports.INFLATE = 2;
exports.GZIP = 3;
exports.GUNZIP = 4;
exports.DEFLATERAW = 5;
exports.INFLATERAW = 6;
exports.UNZIP = 7;

var GZIP_HEADER_ID1 = 0x1f;
var GZIP_HEADER_ID2 = 0x8b;

/**
 * Emulate Node's zlib C++ layer for use by the JS layer in index.js
 */
function Zlib(mode) {
  if (typeof mode !== 'number' || mode < exports.DEFLATE || mode > exports.UNZIP) {
    throw new TypeError('Bad argument');
  }

  this.dictionary = null;
  this.err = 0;
  this.flush = 0;
  this.init_done = false;
  this.level = 0;
  this.memLevel = 0;
  this.mode = mode;
  this.strategy = 0;
  this.windowBits = 0;
  this.write_in_progress = false;
  this.pending_close = false;
  this.gzip_id_bytes_read = 0;
}

Zlib.prototype.close = function () {
  if (this.write_in_progress) {
    this.pending_close = true;
    return;
  }

  this.pending_close = false;

  assert(this.init_done, 'close before init');
  assert(this.mode <= exports.UNZIP);

  if (this.mode === exports.DEFLATE || this.mode === exports.GZIP || this.mode === exports.DEFLATERAW) {
    zlib_deflate.deflateEnd(this.strm);
  } else if (this.mode === exports.INFLATE || this.mode === exports.GUNZIP || this.mode === exports.INFLATERAW || this.mode === exports.UNZIP) {
    zlib_inflate.inflateEnd(this.strm);
  }

  this.mode = exports.NONE;

  this.dictionary = null;
};

Zlib.prototype.write = function (flush, input, in_off, in_len, out, out_off, out_len) {
  return this._write(true, flush, input, in_off, in_len, out, out_off, out_len);
};

Zlib.prototype.writeSync = function (flush, input, in_off, in_len, out, out_off, out_len) {
  return this._write(false, flush, input, in_off, in_len, out, out_off, out_len);
};

Zlib.prototype._write = function (async, flush, input, in_off, in_len, out, out_off, out_len) {
  assert.equal(arguments.length, 8);

  assert(this.init_done, 'write before init');
  assert(this.mode !== exports.NONE, 'already finalized');
  assert.equal(false, this.write_in_progress, 'write already in progress');
  assert.equal(false, this.pending_close, 'close is pending');

  this.write_in_progress = true;

  assert.equal(false, flush === undefined, 'must provide flush value');

  this.write_in_progress = true;

  if (flush !== exports.Z_NO_FLUSH && flush !== exports.Z_PARTIAL_FLUSH && flush !== exports.Z_SYNC_FLUSH && flush !== exports.Z_FULL_FLUSH && flush !== exports.Z_FINISH && flush !== exports.Z_BLOCK) {
    throw new Error('Invalid flush value');
  }

  if (input == null) {
    input = Buffer.alloc(0);
    in_len = 0;
    in_off = 0;
  }

  this.strm.avail_in = in_len;
  this.strm.input = input;
  this.strm.next_in = in_off;
  this.strm.avail_out = out_len;
  this.strm.output = out;
  this.strm.next_out = out_off;
  this.flush = flush;

  if (!async) {
    // sync version
    this._process();

    if (this._checkError()) {
      return this._afterSync();
    }
    return;
  }

  // async version
  var self = this;
  process.nextTick(function () {
    self._process();
    self._after();
  });

  return this;
};

Zlib.prototype._afterSync = function () {
  var avail_out = this.strm.avail_out;
  var avail_in = this.strm.avail_in;

  this.write_in_progress = false;

  return [avail_in, avail_out];
};

Zlib.prototype._process = function () {
  var next_expected_header_byte = null;

  // If the avail_out is left at 0, then it means that it ran out
  // of room.  If there was avail_out left over, then it means
  // that all of the input was consumed.
  switch (this.mode) {
    case exports.DEFLATE:
    case exports.GZIP:
    case exports.DEFLATERAW:
      this.err = zlib_deflate.deflate(this.strm, this.flush);
      break;
    case exports.UNZIP:
      if (this.strm.avail_in > 0) {
        next_expected_header_byte = this.strm.next_in;
      }

      switch (this.gzip_id_bytes_read) {
        case 0:
          if (next_expected_header_byte === null) {
            break;
          }

          if (this.strm.input[next_expected_header_byte] === GZIP_HEADER_ID1) {
            this.gzip_id_bytes_read = 1;
            next_expected_header_byte++;

            if (this.strm.avail_in === 1) {
              // The only available byte was already read.
              break;
            }
          } else {
            this.mode = exports.INFLATE;
            break;
          }

        // fallthrough
        case 1:
          if (next_expected_header_byte === null) {
            break;
          }

          if (this.strm.input[next_expected_header_byte] === GZIP_HEADER_ID2) {
            this.gzip_id_bytes_read = 2;
            this.mode = exports.GUNZIP;
          } else {
            // There is no actual difference between INFLATE and INFLATERAW
            // (after initialization).
            this.mode = exports.INFLATE;
          }

          break;
        default:
          throw new Error('invalid number of gzip magic number bytes read');
      }

    // fallthrough
    case exports.INFLATE:
    case exports.GUNZIP:
    case exports.INFLATERAW:
      this.err = zlib_inflate.inflate(this.strm, this.flush

      // If data was encoded with dictionary
      );if (this.err === exports.Z_NEED_DICT && this.dictionary) {
        // Load it
        this.err = zlib_inflate.inflateSetDictionary(this.strm, this.dictionary);
        if (this.err === exports.Z_OK) {
          // And try to decode again
          this.err = zlib_inflate.inflate(this.strm, this.flush);
        } else if (this.err === exports.Z_DATA_ERROR) {
          // Both inflateSetDictionary() and inflate() return Z_DATA_ERROR.
          // Make it possible for After() to tell a bad dictionary from bad
          // input.
          this.err = exports.Z_NEED_DICT;
        }
      }
      while (this.strm.avail_in > 0 && this.mode === exports.GUNZIP && this.err === exports.Z_STREAM_END && this.strm.next_in[0] !== 0x00) {
        // Bytes remain in input buffer. Perhaps this is another compressed
        // member in the same archive, or just trailing garbage.
        // Trailing zero bytes are okay, though, since they are frequently
        // used for padding.

        this.reset();
        this.err = zlib_inflate.inflate(this.strm, this.flush);
      }
      break;
    default:
      throw new Error('Unknown mode ' + this.mode);
  }
};

Zlib.prototype._checkError = function () {
  // Acceptable error states depend on the type of zlib stream.
  switch (this.err) {
    case exports.Z_OK:
    case exports.Z_BUF_ERROR:
      if (this.strm.avail_out !== 0 && this.flush === exports.Z_FINISH) {
        this._error('unexpected end of file');
        return false;
      }
      break;
    case exports.Z_STREAM_END:
      // normal statuses, not fatal
      break;
    case exports.Z_NEED_DICT:
      if (this.dictionary == null) {
        this._error('Missing dictionary');
      } else {
        this._error('Bad dictionary');
      }
      return false;
    default:
      // something else.
      this._error('Zlib error');
      return false;
  }

  return true;
};

Zlib.prototype._after = function () {
  if (!this._checkError()) {
    return;
  }

  var avail_out = this.strm.avail_out;
  var avail_in = this.strm.avail_in;

  this.write_in_progress = false;

  // call the write() cb
  this.callback(avail_in, avail_out);

  if (this.pending_close) {
    this.close();
  }
};

Zlib.prototype._error = function (message) {
  if (this.strm.msg) {
    message = this.strm.msg;
  }
  this.onerror(message, this.err

  // no hope of rescue.
  );this.write_in_progress = false;
  if (this.pending_close) {
    this.close();
  }
};

Zlib.prototype.init = function (windowBits, level, memLevel, strategy, dictionary) {
  assert(arguments.length === 4 || arguments.length === 5, 'init(windowBits, level, memLevel, strategy, [dictionary])');

  assert(windowBits >= 8 && windowBits <= 15, 'invalid windowBits');
  assert(level >= -1 && level <= 9, 'invalid compression level');

  assert(memLevel >= 1 && memLevel <= 9, 'invalid memlevel');

  assert(strategy === exports.Z_FILTERED || strategy === exports.Z_HUFFMAN_ONLY || strategy === exports.Z_RLE || strategy === exports.Z_FIXED || strategy === exports.Z_DEFAULT_STRATEGY, 'invalid strategy');

  this._init(level, windowBits, memLevel, strategy, dictionary);
  this._setDictionary();
};

Zlib.prototype.params = function () {
  throw new Error('deflateParams Not supported');
};

Zlib.prototype.reset = function () {
  this._reset();
  this._setDictionary();
};

Zlib.prototype._init = function (level, windowBits, memLevel, strategy, dictionary) {
  this.level = level;
  this.windowBits = windowBits;
  this.memLevel = memLevel;
  this.strategy = strategy;

  this.flush = exports.Z_NO_FLUSH;

  this.err = exports.Z_OK;

  if (this.mode === exports.GZIP || this.mode === exports.GUNZIP) {
    this.windowBits += 16;
  }

  if (this.mode === exports.UNZIP) {
    this.windowBits += 32;
  }

  if (this.mode === exports.DEFLATERAW || this.mode === exports.INFLATERAW) {
    this.windowBits = -1 * this.windowBits;
  }

  this.strm = new Zstream();

  switch (this.mode) {
    case exports.DEFLATE:
    case exports.GZIP:
    case exports.DEFLATERAW:
      this.err = zlib_deflate.deflateInit2(this.strm, this.level, exports.Z_DEFLATED, this.windowBits, this.memLevel, this.strategy);
      break;
    case exports.INFLATE:
    case exports.GUNZIP:
    case exports.INFLATERAW:
    case exports.UNZIP:
      this.err = zlib_inflate.inflateInit2(this.strm, this.windowBits);
      break;
    default:
      throw new Error('Unknown mode ' + this.mode);
  }

  if (this.err !== exports.Z_OK) {
    this._error('Init error');
  }

  this.dictionary = dictionary;

  this.write_in_progress = false;
  this.init_done = true;
};

Zlib.prototype._setDictionary = function () {
  if (this.dictionary == null) {
    return;
  }

  this.err = exports.Z_OK;

  switch (this.mode) {
    case exports.DEFLATE:
    case exports.DEFLATERAW:
      this.err = zlib_deflate.deflateSetDictionary(this.strm, this.dictionary);
      break;
    default:
      break;
  }

  if (this.err !== exports.Z_OK) {
    this._error('Failed to set dictionary');
  }
};

Zlib.prototype._reset = function () {
  this.err = exports.Z_OK;

  switch (this.mode) {
    case exports.DEFLATE:
    case exports.DEFLATERAW:
    case exports.GZIP:
      this.err = zlib_deflate.deflateReset(this.strm);
      break;
    case exports.INFLATE:
    case exports.INFLATERAW:
    case exports.GUNZIP:
      this.err = zlib_inflate.inflateReset(this.strm);
      break;
    default:
      break;
  }

  if (this.err !== exports.Z_OK) {
    this._error('Failed to reset stream');
  }
};

exports.Zlib = Zlib;