downzip
Version:
Library to enable client-side code to stream potentially large files into a zipped download
229 lines (206 loc) • 9.77 kB
JavaScript
// Based on the implementation specified in: https://pkware.cachefly.net/webdocs/casestudies/APPNOTE.TXT
import WorkerUtils from '../WorkerUtils'
import Crc32 from './Crc32'
import ZipUtils from './ZipUtils'
// Polyfill ReadableStream if not in browser
let ReadableStreamLocal = (typeof ReadableStream == "undefined") ? require('stream').Readable : ReadableStream
const Utils = new WorkerUtils('Zip')
class Zip {
constructor(zip64){
// Enable large zip compatibility?
this.zip64 = zip64
Utils.log(`Started zip with zip64: ${this.zip64}`)
// Setup file record
this.fileRecord = []
this.finished = false
// Setup byte counter
this.byteCounterBig = BigInt(0)
// Setup output stream
this.outputStream = new ReadableStreamLocal({
start: (controller) => {
Utils.log('OutputStream has started!')
this.outputController = controller
},
cancel: () => {
Utils.error('OutputStream has been canceled!')
},
read: () => {}
})
}
// To also work with the node version of readable stream (for testing)
enqueue = (data) => {
this.outputController ? this.outputController.enqueue(data) : this.outputStream.push(data)
}
close = () => {
this.outputController ? this.outputController.close() : this.outputStream.destroy()
}
// Generators
getZip64ExtraField = (fileSizeBig, localFileHeaderOffsetBig) => {
return ZipUtils.createByteArray([
{data: 0x0001, size: 2},
{data: 28, size: 2},
{data: fileSizeBig, size: 8},
{data: fileSizeBig, size: 8},
{data: localFileHeaderOffsetBig, size: 8},
{data: 0, size: 4}
])
}
isWritingFile = () => (this.fileRecord.length > 0 && (this.fileRecord[this.fileRecord.length - 1].done === false))
// API
startFile = (fileName) => {
if(!this.isWritingFile() && !this.finished) {
Utils.log(`Start file: ${fileName}`)
const date = new Date(Date.now())
// Add file to record
this.fileRecord = [
...this.fileRecord,
{
name: fileName,
sizeBig: BigInt(0),
crc: new Crc32(),
done: false,
date,
headerOffsetBig: this.byteCounterBig
}
]
// Generate Local File Header
const nameBuffer = new TextEncoder().encode(fileName)
const header = ZipUtils.createByteArray([
{data: 0x04034B50, size: 4},
{data: 0x002D, size: 2},
{data: 0x0808, size: 2},
{data: 0x0000, size: 2},
{data: ZipUtils.getTimeStruct(date), size: 2},
{data: ZipUtils.getDateStruct(date), size: 2},
{data: 0x00000000, size: 4},
{data: (this.zip64 ? 0xFFFFFFFF : 0x00000000), size: 4},
{data: (this.zip64 ? 0xFFFFFFFF : 0x00000000), size: 4},
{data: nameBuffer.length, size: 2},
{data: (this.zip64 ? 32 : 0), size: 2},
{data: nameBuffer},
{data: (this.zip64 ? this.getZip64ExtraField(BigInt(0), this.byteCounterBig) : [])}
])
// Write header to output stream and add to byte counter
this.enqueue(header)
this.byteCounterBig += BigInt(header.length)
} else {
Utils.error("Tried adding file while adding other file or while zip has finished")
}
}
appendData = (data) => {
try {
if (this.isWritingFile() && !this.finished) {
// Write data to output stream, add to CRC and increment the file and global size counters
this.enqueue(data)
this.byteCounterBig += BigInt(data.length)
this.fileRecord[this.fileRecord.length - 1].crc.append(data)
this.fileRecord[this.fileRecord.length - 1].sizeBig += BigInt(data.length)
} else {
Utils.error('Tried to append file data, but there is no open file!')
}
} catch (e) {
Utils.error(e)
}
}
endFile = () => {
try {
if(this.isWritingFile() && !this.finished) {
const file = this.fileRecord[this.fileRecord.length - 1]
Utils.log(`End file: ${file.name}`)
const dataDescriptor = ZipUtils.createByteArray([
{data: file.crc.get(), size: 4},
{data: file.sizeBig, size: (this.zip64 ? 8 : 4)},
{data: file.sizeBig, size: (this.zip64 ? 8 : 4)}
])
this.enqueue(dataDescriptor)
this.byteCounterBig += BigInt(dataDescriptor.length)
this.fileRecord[this.fileRecord.length - 1].done = true
} else {
Utils.error('Tried to end file, but there is no open file!')
}
} catch (e) {
Utils.error(e)
}
}
finish = () => {
if(!this.isWritingFile() && !this.finished){
Utils.log(`Finishing zip`)
// Write central directory headers
let centralDirectorySizeBig = BigInt(0)
const centralDirectoryStartBig = this.byteCounterBig
this.fileRecord.forEach((file) => {
const {date, crc, sizeBig, name, headerOffsetBig} = file
const nameBuffer = new TextEncoder().encode(name)
const header = ZipUtils.createByteArray([
{data: 0x02014B50, size: 4},
{data: 0x002D, size: 2},
{data: 0x002D, size: 2},
{data: 0x0808, size: 2},
{data: 0x0000, size: 2},
{data: ZipUtils.getTimeStruct(date), size: 2},
{data: ZipUtils.getDateStruct(date), size: 2},
{data: crc.get(), size: 4},
{data: (this.zip64 ? 0xFFFFFFFF : sizeBig), size: 4},
{data: (this.zip64 ? 0xFFFFFFFF : sizeBig), size: 4},
{data: nameBuffer.length, size: 2},
{data: (this.zip64 ? 32 : 0), size: 2},
{data: 0x0000, size: 2},
{data: 0x0000, size: 2},
{data: 0x0000, size: 2},
{data: 0x00000000, size: 4},
{data: (this.zip64 ? 0xFFFFFFFF : headerOffsetBig), size: 4},
{data: nameBuffer},
{data: (this.zip64 ? this.getZip64ExtraField(sizeBig, headerOffsetBig) : [])}
])
this.enqueue(header)
this.byteCounterBig += BigInt(header.length)
centralDirectorySizeBig += BigInt(header.length)
})
if(this.zip64){
// Write zip64 end of central directory record
const zip64EndOfCentralDirectoryRecordStartBig = this.byteCounterBig
const zip64EndOfCentralDirectoryRecord = ZipUtils.createByteArray([
{data: 0x06064b50, size: 4},
{data: 44, size: 8},
{data: 0x002D, size: 2},
{data: 0x002D, size: 2},
{data: 0, size: 4},
{data: 0, size: 4},
{data: this.fileRecord.length, size: 8},
{data: this.fileRecord.length, size: 8},
{data: centralDirectorySizeBig, size: 8},
{data: centralDirectoryStartBig, size: 8}
])
this.enqueue(zip64EndOfCentralDirectoryRecord)
this.byteCounterBig += BigInt(zip64EndOfCentralDirectoryRecord.length)
// Write zip64 end of central directory locator
const zip64EndOfCentralDirectoryLocator = ZipUtils.createByteArray([
{data: 0x07064b50, size: 4},
{data: 0, size: 4},
{data: zip64EndOfCentralDirectoryRecordStartBig, size: 8},
{data: 1, size: 4}
])
this.enqueue(zip64EndOfCentralDirectoryLocator)
this.byteCounterBig += BigInt(zip64EndOfCentralDirectoryLocator.length)
}
const endOfCentralDirectoryRecord = ZipUtils.createByteArray([
{data: 0x06054b50, size: 4},
{data: 0, size: 2},
{data: 0, size: 2},
{data: (this.zip64 ? 0xFFFF : this.fileRecord.length), size: 2},
{data: (this.zip64 ? 0xFFFF : this.fileRecord.length), size: 2},
{data: (this.zip64 ? 0xFFFFFFFF : centralDirectorySizeBig), size: 4},
{data: (this.zip64 ? 0xFFFFFFFF : centralDirectoryStartBig), size: 4},
{data: 0, size: 2}
])
this.enqueue(endOfCentralDirectoryRecord)
this.close()
this.byteCounterBig += BigInt(endOfCentralDirectoryRecord.length)
this.finished = true
Utils.log(`Done writing zip file. Wrote ${this.fileRecord.length} files and a total of ${this.byteCounterBig} bytes.`)
} else {
Utils.error('Empty zip, or there is still a file open')
}
}
}
export default Zip