22

✏️ Editing: entryHeader.js

var Utils = require("../util"),
    Constants = Utils.Constants;

/* The central directory file header */
module.exports = function () {
    var _verMade = 0x14,
        _version = 0x0A,
        _flags = 0,
        _method = 0,
        _time = 0,
        _crc = 0,
        _compressedSize = 0,
        _size = 0,
        _fnameLen = 0,
        _extraLen = 0,

_comLen = 0,
        _diskStart = 0,
        _inattr = 0,
        _attr = 0,
        _offset = 0;

switch(process.platform){
        case 'win32':
            _verMade |= 0x0A00;
        default:
            _verMade |= 0x0300;
    }

var _dataHeader = {};

function setTime(val) {
        val = new Date(val);
        _time = (val.getFullYear() - 1980 & 0x7f) << 25  // b09-16 years from 1980
            | (val.getMonth() + 1) << 21                 // b05-08 month
            | val.getDate() << 16                        // b00-04 hour

// 2 bytes time
            | val.getHours() << 11    // b11-15 hour
            | val.getMinutes() << 5   // b05-10 minute
            | val.getSeconds() >> 1;  // b00-04 seconds divided by 2
    }

setTime(+new Date());

return {
        get made () { return _verMade; },
        set made (val) { _verMade = val; },

get version () { return _version; },
        set version (val) { _version = val },

get flags () { return _flags },
        set flags (val) { _flags = val; },

get method () { return _method; },
        set method (val) {
            switch (val){
                case Constants.STORED:
                    this.version = 10;
                case Constants.DEFLATED:
                default:
                    this.version = 20;
            }
            _method = val;
            },

get time () { return new Date(
            ((_time >> 25) & 0x7f) + 1980,
            ((_time >> 21) & 0x0f) - 1,
            (_time >> 16) & 0x1f,
            (_time >> 11) & 0x1f,
            (_time >> 5) & 0x3f,
            (_time & 0x1f) << 1
        );
        },
        set time (val) {
            setTime(val);
        },

get crc () { return _crc; },
        set crc (val) { _crc = val; },

get compressedSize () { return _compressedSize; },
        set compressedSize (val) { _compressedSize = val; },

get size () { return _size; },
        set size (val) { _size = val; },

get fileNameLength () { return _fnameLen; },
        set fileNameLength (val) { _fnameLen = val; },

get extraLength () { return _extraLen },
        set extraLength (val) { _extraLen = val; },

get commentLength () { return _comLen },
        set commentLength (val) { _comLen = val },

get diskNumStart () { return _diskStart },
        set diskNumStart (val) { _diskStart = val },

get inAttr () { return _inattr },
        set inAttr (val) { _inattr = val },

get attr () { return _attr },
        set attr (val) { _attr = val },

get offset () { return _offset },
        set offset (val) { _offset = val },

get encripted () { return (_flags & 1) === 1 },

get entryHeaderSize () {
            return Constants.CENHDR + _fnameLen + _extraLen + _comLen;
        },

get realDataOffset () {
            return _offset + Constants.LOCHDR + _dataHeader.fnameLen + _dataHeader.extraLen;
        },

get dataHeader () {
            return _dataHeader;
        },

loadDataHeaderFromBinary : function(/*Buffer*/input) {
            var data = input.slice(_offset, _offset + Constants.LOCHDR);
            // 30 bytes and should start with "PK\003\004"
            if (data.readUInt32LE(0) !== Constants.LOCSIG) {
                throw new Error(Utils.Errors.INVALID_LOC);
            }
            _dataHeader = {
                // version needed to extract
                version : data.readUInt16LE(Constants.LOCVER),
                // general purpose bit flag
                flags : data.readUInt16LE(Constants.LOCFLG),
                // compression method
                method : data.readUInt16LE(Constants.LOCHOW),
                // modification time (2 bytes time, 2 bytes date)
                time : data.readUInt32LE(Constants.LOCTIM),
                // uncompressed file crc-32 value
                crc : data.readUInt32LE(Constants.LOCCRC),
                // compressed size
                compressedSize : data.readUInt32LE(Constants.LOCSIZ),
                // uncompressed size
                size : data.readUInt32LE(Constants.LOCLEN),
                // filename length
                fnameLen : data.readUInt16LE(Constants.LOCNAM),
                // extra field length
                extraLen : data.readUInt16LE(Constants.LOCEXT)
            }
        },

loadFromBinary : function(/*Buffer*/data) {
            // data should be 46 bytes and start with "PK 01 02"
            if (data.length !== Constants.CENHDR || data.readUInt32LE(0) !== Constants.CENSIG) {
                throw new Error(Utils.Errors.INVALID_CEN);
            }
            // version made by
            _verMade = data.readUInt16LE(Constants.CENVEM);
            // version needed to extract
            _version = data.readUInt16LE(Constants.CENVER);
            // encrypt, decrypt flags
            _flags = data.readUInt16LE(Constants.CENFLG);
            // compression method
            _method = data.readUInt16LE(Constants.CENHOW);
            // modification time (2 bytes time, 2 bytes date)
            _time = data.readUInt32LE(Constants.CENTIM);
            // uncompressed file crc-32 value
            _crc = data.readUInt32LE(Constants.CENCRC);
            // compressed size
            _compressedSize = data.readUInt32LE(Constants.CENSIZ);
            // uncompressed size
            _size = data.readUInt32LE(Constants.CENLEN);
            // filename length
            _fnameLen = data.readUInt16LE(Constants.CENNAM);
            // extra field length
            _extraLen = data.readUInt16LE(Constants.CENEXT);
            // file comment length
            _comLen = data.readUInt16LE(Constants.CENCOM);
            // volume number start
            _diskStart = data.readUInt16LE(Constants.CENDSK);
            // internal file attributes
            _inattr = data.readUInt16LE(Constants.CENATT);
            // external file attributes
            _attr = data.readUInt32LE(Constants.CENATX);
            // LOC header offset
            _offset = data.readUInt32LE(Constants.CENOFF);
        },

dataHeaderToBinary : function() {
            // LOC header size (30 bytes)
            var data = Buffer.alloc(Constants.LOCHDR);
            // "PK\003\004"
            data.writeUInt32LE(Constants.LOCSIG, 0);
            // version needed to extract
            data.writeUInt16LE(_version, Constants.LOCVER);
            // general purpose bit flag
            data.writeUInt16LE(_flags, Constants.LOCFLG);
            // compression method
            data.writeUInt16LE(_method, Constants.LOCHOW);
            // modification time (2 bytes time, 2 bytes date)
            data.writeUInt32LE(_time, Constants.LOCTIM);
            // uncompressed file crc-32 value
            data.writeUInt32LE(_crc, Constants.LOCCRC);
            // compressed size
            data.writeUInt32LE(_compressedSize, Constants.LOCSIZ);
            // uncompressed size
            data.writeUInt32LE(_size, Constants.LOCLEN);
            // filename length
            data.writeUInt16LE(_fnameLen, Constants.LOCNAM);
            // extra field length
            data.writeUInt16LE(_extraLen, Constants.LOCEXT);
            return data;
        },

entryHeaderToBinary : function() {
            // CEN header size (46 bytes)
            var data = Buffer.alloc(Constants.CENHDR + _fnameLen + _extraLen + _comLen);
            // "PK\001\002"
            data.writeUInt32LE(Constants.CENSIG, 0);
            // version made by
            data.writeUInt16LE(_verMade, Constants.CENVEM);
            // version needed to extract
            data.writeUInt16LE(_version, Constants.CENVER);
            // encrypt, decrypt flags
            data.writeUInt16LE(_flags, Constants.CENFLG);
            // compression method
            data.writeUInt16LE(_method, Constants.CENHOW);
            // modification time (2 bytes time, 2 bytes date)
            data.writeUInt32LE(_time, Constants.CENTIM);
            // uncompressed file crc-32 value
            data.writeUInt32LE(_crc, Constants.CENCRC);
            // compressed size
            data.writeUInt32LE(_compressedSize, Constants.CENSIZ);
            // uncompressed size
            data.writeUInt32LE(_size, Constants.CENLEN);
            // filename length
            data.writeUInt16LE(_fnameLen, Constants.CENNAM);
            // extra field length
            data.writeUInt16LE(_extraLen, Constants.CENEXT);
            // file comment length
            data.writeUInt16LE(_comLen, Constants.CENCOM);
            // volume number start
            data.writeUInt16LE(_diskStart, Constants.CENDSK);
            // internal file attributes
            data.writeUInt16LE(_inattr, Constants.CENATT);
            // external file attributes
            data.writeUInt32LE(_attr, Constants.CENATX);
            // LOC header offset
            data.writeUInt32LE(_offset, Constants.CENOFF);
            // fill all with
            data.fill(0x00, Constants.CENHDR);
            return data;
        },

toString : function() {
            return '{\n' +
                '\t"made" : ' + _verMade + ",\n" +
                '\t"version" : ' + _version + ",\n" +
                '\t"flags" : ' + _flags + ",\n" +
                '\t"method" : ' + Utils.methodToString(_method) + ",\n" +
                '\t"time" : ' + this.time + ",\n" +
                '\t"crc" : 0x' + _crc.toString(16).toUpperCase() + ",\n" +
                '\t"compressedSize" : ' + _compressedSize + " bytes,\n" +
                '\t"size" : ' + _size + " bytes,\n" +
                '\t"fileNameLength" : ' + _fnameLen + ",\n" +
                '\t"extraLength" : ' + _extraLen + " bytes,\n" +
                '\t"commentLength" : ' + _comLen + " bytes,\n" +
                '\t"diskNumStart" : ' + _diskStart + ",\n" +
                '\t"inAttr" : ' + _inattr + ",\n" +
                '\t"attr" : ' + _attr + ",\n" +
                '\t"offset" : ' + _offset + ",\n" +
                '\t"entryHeaderSize" : ' + (Constants.CENHDR + _fnameLen + _extraLen + _comLen) + " bytes\n" +
                '}';
        }
    }
};

MR SKB