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Mini Shell
'use strict'
const assert = require('assert')
const Buffer = require('buffer').Buffer
const binding = process.binding('zlib')
const constants = exports.constants = require('./constants.js')
const MiniPass = require('minipass')
class ZlibError extends Error {
constructor (msg, errno) {
super('zlib: ' + msg)
this.errno = errno
this.code = codes.get(errno)
}
get name () {
return 'ZlibError'
}
}
// translation table for return codes.
const codes = new Map([
[constants.Z_OK, 'Z_OK'],
[constants.Z_STREAM_END, 'Z_STREAM_END'],
[constants.Z_NEED_DICT, 'Z_NEED_DICT'],
[constants.Z_ERRNO, 'Z_ERRNO'],
[constants.Z_STREAM_ERROR, 'Z_STREAM_ERROR'],
[constants.Z_DATA_ERROR, 'Z_DATA_ERROR'],
[constants.Z_MEM_ERROR, 'Z_MEM_ERROR'],
[constants.Z_BUF_ERROR, 'Z_BUF_ERROR'],
[constants.Z_VERSION_ERROR, 'Z_VERSION_ERROR']
])
const validFlushFlags = new Set([
constants.Z_NO_FLUSH,
constants.Z_PARTIAL_FLUSH,
constants.Z_SYNC_FLUSH,
constants.Z_FULL_FLUSH,
constants.Z_FINISH,
constants.Z_BLOCK
])
const strategies = new Set([
constants.Z_FILTERED,
constants.Z_HUFFMAN_ONLY,
constants.Z_RLE,
constants.Z_FIXED,
constants.Z_DEFAULT_STRATEGY
])
// the Zlib class they all inherit from
// This thing manages the queue of requests, and returns
// true or false if there is anything in the queue when
// you call the .write() method.
const _opts = Symbol('opts')
const _chunkSize = Symbol('chunkSize')
const _flushFlag = Symbol('flushFlag')
const _finishFlush = Symbol('finishFlush')
const _handle = Symbol('handle')
const _hadError = Symbol('hadError')
const _buffer = Symbol('buffer')
const _offset = Symbol('offset')
const _level = Symbol('level')
const _strategy = Symbol('strategy')
const _ended = Symbol('ended')
const _writeState = Symbol('writeState')
class Zlib extends MiniPass {
constructor (opts, mode) {
super(opts)
this[_ended] = false
this[_opts] = opts = opts || {}
this[_chunkSize] = opts.chunkSize || constants.Z_DEFAULT_CHUNK
if (opts.flush && !validFlushFlags.has(opts.flush)) {
throw new TypeError('Invalid flush flag: ' + opts.flush)
}
if (opts.finishFlush && !validFlushFlags.has(opts.finishFlush)) {
throw new TypeError('Invalid flush flag: ' + opts.finishFlush)
}
this[_flushFlag] = opts.flush || constants.Z_NO_FLUSH
this[_finishFlush] = typeof opts.finishFlush !== 'undefined' ?
opts.finishFlush : constants.Z_FINISH
if (opts.chunkSize) {
if (opts.chunkSize < constants.Z_MIN_CHUNK) {
throw new RangeError('Invalid chunk size: ' + opts.chunkSize)
}
}
if (opts.windowBits) {
if (opts.windowBits < constants.Z_MIN_WINDOWBITS ||
opts.windowBits > constants.Z_MAX_WINDOWBITS) {
throw new RangeError('Invalid windowBits: ' + opts.windowBits)
}
}
if (opts.level) {
if (opts.level < constants.Z_MIN_LEVEL ||
opts.level > constants.Z_MAX_LEVEL) {
throw new RangeError('Invalid compression level: ' + opts.level)
}
}
if (opts.memLevel) {
if (opts.memLevel < constants.Z_MIN_MEMLEVEL ||
opts.memLevel > constants.Z_MAX_MEMLEVEL) {
throw new RangeError('Invalid memLevel: ' + opts.memLevel)
}
}
if (opts.strategy && !(strategies.has(opts.strategy)))
throw new TypeError('Invalid strategy: ' + opts.strategy)
if (opts.dictionary) {
if (!(opts.dictionary instanceof Buffer)) {
throw new TypeError('Invalid dictionary: it should be a Buffer instance')
}
}
this[_handle] = new binding.Zlib(mode)
this[_hadError] = false
this[_handle].onerror = (message, errno) => {
// there is no way to cleanly recover.
// continuing only obscures problems.
this.close()
this[_hadError] = true
const error = new ZlibError(message, errno)
this.emit('error', error)
}
const level = typeof opts.level === 'number' ? opts.level
: constants.Z_DEFAULT_COMPRESSION
var strategy = typeof opts.strategy === 'number' ? opts.strategy
: constants.Z_DEFAULT_STRATEGY
this[_writeState] = new Uint32Array(2);
const window = opts.windowBits || constants.Z_DEFAULT_WINDOWBITS
const memLevel = opts.memLevel || constants.Z_DEFAULT_MEMLEVEL
// API changed in node v9
/* istanbul ignore next */
if (/^v[0-8]\./.test(process.version)) {
this[_handle].init(window,
level,
memLevel,
strategy,
opts.dictionary)
} else {
this[_handle].init(window,
level,
memLevel,
strategy,
this[_writeState],
() => {},
opts.dictionary)
}
this[_buffer] = Buffer.allocUnsafe(this[_chunkSize])
this[_offset] = 0
this[_level] = level
this[_strategy] = strategy
this.once('end', this.close)
}
close () {
if (this[_handle]) {
this[_handle].close()
this[_handle] = null
this.emit('close')
}
}
params (level, strategy) {
if (!this[_handle])
throw new Error('cannot switch params when binding is closed')
// no way to test this without also not supporting params at all
/* istanbul ignore if */
if (!this[_handle].params)
throw new Error('not supported in this implementation')
if (level < constants.Z_MIN_LEVEL ||
level > constants.Z_MAX_LEVEL) {
throw new RangeError('Invalid compression level: ' + level)
}
if (!(strategies.has(strategy)))
throw new TypeError('Invalid strategy: ' + strategy)
if (this[_level] !== level || this[_strategy] !== strategy) {
this.flush(constants.Z_SYNC_FLUSH)
assert(this[_handle], 'zlib binding closed')
this[_handle].params(level, strategy)
/* istanbul ignore else */
if (!this[_hadError]) {
this[_level] = level
this[_strategy] = strategy
}
}
}
reset () {
assert(this[_handle], 'zlib binding closed')
return this[_handle].reset()
}
flush (kind) {
if (kind === undefined)
kind = constants.Z_FULL_FLUSH
if (this.ended)
return
const flushFlag = this[_flushFlag]
this[_flushFlag] = kind
this.write(Buffer.alloc(0))
this[_flushFlag] = flushFlag
}
end (chunk, encoding, cb) {
if (chunk)
this.write(chunk, encoding)
this.flush(this[_finishFlush])
this[_ended] = true
return super.end(null, null, cb)
}
get ended () {
return this[_ended]
}
write (chunk, encoding, cb) {
// process the chunk using the sync process
// then super.write() all the outputted chunks
if (typeof encoding === 'function')
cb = encoding, encoding = 'utf8'
if (typeof chunk === 'string')
chunk = Buffer.from(chunk, encoding)
let availInBefore = chunk && chunk.length
let availOutBefore = this[_chunkSize] - this[_offset]
let inOff = 0 // the offset of the input buffer
const flushFlag = this[_flushFlag]
let writeReturn = true
assert(this[_handle], 'zlib binding closed')
do {
let res = this[_handle].writeSync(
flushFlag,
chunk, // in
inOff, // in_off
availInBefore, // in_len
this[_buffer], // out
this[_offset], //out_off
availOutBefore // out_len
)
if (this[_hadError])
break
// API changed in v9
/* istanbul ignore next */
let availInAfter = res ? res[0] : this[_writeState][1]
/* istanbul ignore next */
let availOutAfter = res ? res[1] : this[_writeState][0]
const have = availOutBefore - availOutAfter
assert(have >= 0, 'have should not go down')
if (have > 0) {
const out = this[_buffer].slice(
this[_offset], this[_offset] + have
)
this[_offset] += have
// serve some output to the consumer.
writeReturn = super.write(out) && writeReturn
}
// exhausted the output buffer, or used all the input create a new one.
if (availOutAfter === 0 || this[_offset] >= this[_chunkSize]) {
availOutBefore = this[_chunkSize]
this[_offset] = 0
this[_buffer] = Buffer.allocUnsafe(this[_chunkSize])
}
if (availOutAfter === 0) {
// Not actually done. Need to reprocess.
// Also, update the availInBefore to the availInAfter value,
// so that if we have to hit it a third (fourth, etc.) time,
// it'll have the correct byte counts.
inOff += (availInBefore - availInAfter)
availInBefore = availInAfter
continue
}
break
} while (!this[_hadError])
if (cb)
cb()
return writeReturn
}
}
// minimal 2-byte header
class Deflate extends Zlib {
constructor (opts) {
super(opts, constants.DEFLATE)
}
}
class Inflate extends Zlib {
constructor (opts) {
super(opts, constants.INFLATE)
}
}
// gzip - bigger header, same deflate compression
class Gzip extends Zlib {
constructor (opts) {
super(opts, constants.GZIP)
}
}
class Gunzip extends Zlib {
constructor (opts) {
super(opts, constants.GUNZIP)
}
}
// raw - no header
class DeflateRaw extends Zlib {
constructor (opts) {
super(opts, constants.DEFLATERAW)
}
}
class InflateRaw extends Zlib {
constructor (opts) {
super(opts, constants.INFLATERAW)
}
}
// auto-detect header.
class Unzip extends Zlib {
constructor (opts) {
super(opts, constants.UNZIP)
}
}
exports.Deflate = Deflate
exports.Inflate = Inflate
exports.Gzip = Gzip
exports.Gunzip = Gunzip
exports.DeflateRaw = DeflateRaw
exports.InflateRaw = InflateRaw
exports.Unzip = Unzip
Zerion Mini Shell 1.0