File size: 4,883 Bytes
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/**
* Ref https://pkware.cachefly.net/webdocs/casestudies/APPNOTE.TXT
*/
import { UINT16_LE, UINT32_LE } from "token-types";
export const Signature = {
LocalFileHeader: 0x04034b50,
DataDescriptor: 0x08074b50,
CentralFileHeader: 0x02014b50,
EndOfCentralDirectory: 0x06054b50
};
export const DataDescriptor = {
get(array) {
const flags = UINT16_LE.get(array, 6);
return {
signature: UINT32_LE.get(array, 0),
compressedSize: UINT32_LE.get(array, 8),
uncompressedSize: UINT32_LE.get(array, 12),
};
}, len: 16
};
/**
* First part of the ZIP Local File Header
* Offset | Bytes| Description
* -------|------+-------------------------------------------------------------------
* 0 | 4 | Signature (0x04034b50)
* 4 | 2 | Minimum version needed to extract
* 6 | 2 | Bit flag
* 8 | 2 | Compression method
* 10 | 2 | File last modification time (MS-DOS format)
* 12 | 2 | File last modification date (MS-DOS format)
* 14 | 4 | CRC-32 of uncompressed data
* 18 | 4 | Compressed size
* 22 | 4 | Uncompressed size
* 26 | 2 | File name length (n)
* 28 | 2 | Extra field length (m)
* 30 | n | File name
* 30 + n | m | Extra field
*/
export const LocalFileHeaderToken = {
get(array) {
const flags = UINT16_LE.get(array, 6);
return {
signature: UINT32_LE.get(array, 0),
minVersion: UINT16_LE.get(array, 4),
dataDescriptor: !!(flags & 0x0008),
compressedMethod: UINT16_LE.get(array, 8),
compressedSize: UINT32_LE.get(array, 18),
uncompressedSize: UINT32_LE.get(array, 22),
filenameLength: UINT16_LE.get(array, 26),
extraFieldLength: UINT16_LE.get(array, 28),
filename: null
};
}, len: 30
};
/**
* 4.3.16 End of central directory record:
* end of central dir signature (0x06064b50) 4 bytes
* number of this disk 2 bytes
* number of the disk with the start of the central directory 2 bytes
* total number of entries in the central directory on this disk 2 bytes
* total number of entries in the size of the central directory 2 bytes
* sizeOfTheCentralDirectory 4 bytes
* offset of start of central directory with respect to the starting disk number 4 bytes
* .ZIP file comment length 2 bytes
* .ZIP file comment (variable size)
*/
export const EndOfCentralDirectoryRecordToken = {
get(array) {
return {
signature: UINT32_LE.get(array, 0),
nrOfThisDisk: UINT16_LE.get(array, 4),
nrOfThisDiskWithTheStart: UINT16_LE.get(array, 6),
nrOfEntriesOnThisDisk: UINT16_LE.get(array, 8),
nrOfEntriesOfSize: UINT16_LE.get(array, 10),
sizeOfCd: UINT32_LE.get(array, 12),
offsetOfStartOfCd: UINT32_LE.get(array, 16),
zipFileCommentLength: UINT16_LE.get(array, 20),
};
}, len: 22
};
/**
* File header:
* central file header signature 4 bytes 0 (0x02014b50)
* version made by 2 bytes 4
* version needed to extract 2 bytes 6
* general purpose bit flag 2 bytes 8
* compression method 2 bytes 10
* last mod file time 2 bytes 12
* last mod file date 2 bytes 14
* crc-32 4 bytes 16
* compressed size 4 bytes 20
* uncompressed size 4 bytes 24
* file name length 2 bytes 28
* extra field length 2 bytes 30
* file comment length 2 bytes 32
* disk number start 2 bytes 34
* internal file attributes 2 bytes 36
* external file attributes 4 bytes 38
* relative offset of local header 4 bytes 42
*/
export const FileHeader = {
get(array) {
const flags = UINT16_LE.get(array, 8);
return {
signature: UINT32_LE.get(array, 0),
minVersion: UINT16_LE.get(array, 6),
dataDescriptor: !!(flags & 0x0008),
compressedMethod: UINT16_LE.get(array, 10),
compressedSize: UINT32_LE.get(array, 20),
uncompressedSize: UINT32_LE.get(array, 24),
filenameLength: UINT16_LE.get(array, 28),
extraFieldLength: UINT16_LE.get(array, 30),
fileCommentLength: UINT16_LE.get(array, 32),
relativeOffsetOfLocalHeader: UINT32_LE.get(array, 42),
filename: null
};
}, len: 46
};
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