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337import { ReadableStreamLike } from './conversions';
import { ReadableStreamBlockReader } from './reader';
import {
BLOCK_SIZE,
CHECKSUM_INITIAL,
TarTypeFlag,
InternalTypeFlag,
TarHeader,
TarFile,
TarChunk,
initTarHeader,
blockPad,
} from './tarShared';
const DECODER = new TextDecoder();
async function decodePax(
reader: ReadableStreamBlockReader,
gax: TarHeader | null,
header: TarHeader
) {
let remaining = header.size;
let pax = '';
while (remaining > 0) {
let block = await reader.read();
if (!block)
throw new Error('Invalid Tar: Unexpected EOF while parsing PAX data');
remaining -= block.byteLength;
if (remaining < 0) block = block.subarray(0, remaining);
pax += DECODER.decode(block, { stream: true });
}
for (let from = 0, to = 0; from < pax.length; to = 0) {
while (to < pax.length && pax.charCodeAt(to) !== 32) to++;
const length = parseInt(pax.slice(from, to), 10);
if (!length || length != length) break;
if (pax.charCodeAt(from + length - 1) !== 10) break;
const entry = pax.slice(to + 1, from + length - 1);
const keyIndex = entry.indexOf('=');
if (keyIndex === -1) break;
const key = entry.slice(0, keyIndex);
const value = entry.slice(keyIndex + 1);
from += length;
switch (key) {
case 'path':
if (gax) gax._paxName = value;
header._paxName = value;
break;
case 'linkpath':
if (gax) gax._paxLinkName = value;
header._paxLinkName = value;
break;
case 'size':
if (gax) gax._paxSize = +value;
header._paxSize = +value;
break;
case 'gid':
case 'uid':
case 'mode':
case 'mtime':
if (gax) gax[key] = +value;
header[key] = +value;
break;
case 'uname':
case 'gname':
if (gax) gax[key] = value;
header[key] = value;
break;
}
}
}
function getTypeFlag(
bytes: Uint8Array
): TarTypeFlag | InternalTypeFlag | ({} & number) {
return bytes[156];
}
function checkMagic(bytes: Uint8Array): boolean {
return (
bytes[257] === 0x75 &&
bytes[258] === 0x73 &&
bytes[259] === 0x74 &&
bytes[260] === 0x61 &&
bytes[261] === 0x72 &&
(bytes[262] === 0x00 || bytes[262] === 0x20)
);
}
function checkChecksum(bytes: Uint8Array): number {
let sum = CHECKSUM_INITIAL;
const chksum = decodeOctal(bytes, 148, 156);
if (chksum === sum) return sum;
for (let idx = 0; idx < 148; idx++) sum += bytes[idx];
for (let idx = 156; idx < 512; idx++) sum += bytes[idx];
return sum === chksum ? sum : 0;
}
function decodeString(bytes: Uint8Array, from: number, to: number): string {
let end = from;
while (end < to && bytes[end] !== 0) end++;
return end > from ? DECODER.decode(bytes.subarray(from, end)) : '';
}
async function decodeLongString(
reader: ReadableStreamBlockReader,
size: number
): Promise<string> {
let remaining = size;
let output = '';
let endIndex = -1;
while (remaining > 0) {
let block = await reader.read();
if (!block)
throw new Error('Invalid Tar: Unexpected EOF while parsing long string');
if (endIndex === -1) {
// We fundamentally don't trust that the length is accurate, and we cut off
// any strings we parse at the trailing zero byte
endIndex = block.indexOf(0);
if (endIndex > -1) block = block.subarray(0, endIndex);
output += DECODER.decode(block, { stream: true });
}
break;
}
output += DECODER.decode();
return output;
}
function decodeOctal(bytes: Uint8Array, from: number, to: number): number {
const end = to - 1;
let val = 0;
let idx = to;
if (bytes[from] === 0x80) {
while (idx-- > from + 1) val += bytes[idx] * 256 ** (end - idx);
return val;
} else if (bytes[from] === 0xff) {
let flipped = false;
while (idx-- > from) {
const f = flipped
? 0xff ^ bytes[idx] // ones comp
: (0xff ^ bytes[idx]) + 1; // twos comp
val -= (f & 0xff) * 256 ** (end - idx);
flipped ||= bytes[idx] !== 0;
}
return val;
} else {
idx = from;
while (idx < to && (bytes[idx] === 32 || bytes[idx] === 0)) idx++;
if (end !== idx) val = parseInt(decodeString(bytes, idx, to), 8);
return val == val ? val || 0 : 0;
}
}
function decodeBase(header: TarHeader, buffer: Uint8Array): void {
/*
| Field Name | Offset | Length | Field Type |
| ---------- | ------ | ------ | -------------------------- |
| name | 0 B | 100 B | NUL-terminated if NUL fits |
| mode | 100 B | 8 B | |
| uid | 108 B | 8 B | |
| gid | 116 B | 8 B | |
| size | 124 B | 12 B | |
| mtime | 136 B | 12 B | |
| chksum | 148 B | 8 B | |
| typeflag | 156 B | 1 B | see below |
| linkname | 157 B | 100 B | NUL-terminated if NUL fits |
| magic | 257 B | 6 B | must be TMAGIC (NUL term.) |
| version | 263 B | 2 B | must be TVERSION |
| uname | 265 B | 32 B | NUL-terminated |
| gname | 297 B | 32 B | NUL-terminated |
| devmajor | 329 B | 8 B | |
| devminor | 337 B | 8 B | |
| prefix | 345 B | 155 B | NUL-terminated if NUL fits |
*/
header.name = decodeString(buffer, 0, 100);
header.mode ||= decodeOctal(buffer, 100, 108);
header.uid ||= decodeOctal(buffer, 108, 116);
header.gid ||= decodeOctal(buffer, 116, 124);
header.size = decodeOctal(buffer, 124, 136);
header.mtime ||= decodeOctal(buffer, 136, 148);
// CHECKSUM: 148 - 156
header.typeflag = getTypeFlag(buffer);
header.linkname = decodeString(buffer, 157, 257) || null;
// TMAGIC: 257 - 263
// TVERSION: 263 - 265
header.uname ||= decodeString(buffer, 265, 297) || null;
header.gname ||= decodeString(buffer, 297, 329) || null;
header.devmajor = decodeOctal(buffer, 329, 337);
header.devminor = decodeOctal(buffer, 337, 345);
if (buffer[345] !== 0) {
header._prefix = decodeString(buffer, 345, 500);
}
if (
header.typeflag === InternalTypeFlag.OLD_FILE &&
header.name.endsWith('/')
) {
header.typeflag = TarTypeFlag.DIRECTORY;
}
}
async function decodeHeader(
reader: ReadableStreamBlockReader,
gax: TarHeader
): Promise<TarHeader | undefined> {
let buffer: Uint8Array | null;
let header = initTarHeader(gax);
while ((buffer = await reader.read()) && checkMagic(buffer)) {
switch (getTypeFlag(buffer)) {
case InternalTypeFlag.LONG_NAME:
case InternalTypeFlag.OLD_LONG_NAME:
decodeBase(header, buffer);
header._longName = await decodeLongString(reader, header.size);
continue;
case InternalTypeFlag.LONG_LINK_NAME:
decodeBase(header, buffer);
header._longLinkName = await decodeLongString(reader, header.size);
continue;
case InternalTypeFlag.GAX:
decodeBase(header, buffer);
await decodePax(reader, gax, header);
continue;
case InternalTypeFlag.PAX:
decodeBase(header, buffer);
await decodePax(reader, null, header);
continue;
case InternalTypeFlag.OLD_FILE:
case InternalTypeFlag.CONTIGUOUS_FILE:
case TarTypeFlag.FILE:
case TarTypeFlag.LINK:
case TarTypeFlag.SYMLINK:
case TarTypeFlag.DIRECTORY:
decodeBase(header, buffer);
return header;
default:
// Usually we don't check the checksum, but if we don't know the type, we should
// double check it. If it's invalid we can be sure we have an invalid block
if (!checkChecksum(buffer)) {
throw new Error(
'Invalid Tar: Unexpected block with invalid checksum'
);
}
decodeBase(header, buffer);
return header;
}
}
for (let idx = 0; buffer && idx < buffer.byteLength; idx++)
if (buffer[idx] !== 0)
throw new Error('Invalid Tar: Unexpected non-header block');
return undefined;
}
// NOTE(@kitten): We don't really want to copy but something isn't applying backpressure correctly
function copyUint8Array(src: Uint8Array) {
const dst = new Uint8Array(src.byteLength);
dst.set(src);
return dst;
}
/** Provide tar entry iterator */
export async function* untar(
stream: ReadableStreamLike<Uint8Array>
): AsyncGenerator<TarFile | TarChunk> {
const gax = initTarHeader(null);
const reader = new ReadableStreamBlockReader(stream, BLOCK_SIZE);
const streamParams = new ByteLengthQueuingStrategy({ highWaterMark: 0 });
let header: TarHeader | undefined;
while ((header = await decodeHeader(reader, gax)) != null) {
const pad = blockPad(header.size);
let consumedTrailer = pad === 0;
let remaining = header._paxSize || header.size;
let cancel: () => Promise<void>;
const stream = new ReadableStream(
{
// NOTE(@kitten): This is needed in Cloudflare to attach the expected size to the stream
expectedLength: header.size,
cancel: (cancel = async function cancel() {
if (!consumedTrailer) {
consumedTrailer = true;
remaining += pad;
}
if (remaining > 0) {
const skipped = await reader.skip(remaining);
if (skipped > 0) throw new Error('Invalid Tar: Unexpected EOF');
remaining = 0;
}
}),
async pull(controller) {
if (remaining) {
const buffer = await reader.pull(remaining);
if (!buffer) throw new Error('Invalid Tar: Unexpected EOF');
remaining -= buffer.byteLength;
controller.enqueue(copyUint8Array(buffer));
}
if (!remaining) {
if (!consumedTrailer) {
consumedTrailer = true;
const skipped = await reader.skip(pad);
if (skipped > 0) throw new Error('Invalid Tar: Unexpected EOF');
}
controller.close();
}
},
},
streamParams
);
let chunk: TarFile | TarChunk;
switch (header.typeflag) {
case InternalTypeFlag.OLD_FILE:
case InternalTypeFlag.CONTIGUOUS_FILE:
case TarTypeFlag.FILE:
chunk = new TarFile(stream, header);
break;
case TarTypeFlag.LINK:
case TarTypeFlag.SYMLINK:
case TarTypeFlag.DIRECTORY:
chunk = new TarChunk(stream, header);
break;
default:
await cancel();
continue;
}
yield chunk;
if (remaining > 0 || !consumedTrailer) {
await (stream.locked ? cancel() : stream.cancel());
}
}
}