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255import {
type ReadableStreamLike,
streamLikeToIterator,
streamToIterator,
} from './conversions';
import {
BLOCK_SIZE,
CHECKSUM_INITIAL,
TarTypeFlag,
InternalTypeFlag,
TarHeader,
TarFile,
TarChunk,
initTarHeader,
blockPad,
} from './tarShared';
const MAX_NAME_LEN = 100;
const MAX_PREFIX_LEN = 155;
const ENCODER = new TextEncoder();
const MAGIC = 'ustar\0' + '00';
// See: https://github.com/mafintosh/tar-stream/blob/126968f/constants.js#L1C1-L8C2
function modeToType(mode: number) {
switch (mode & 61440 /*S_IFMT*/) {
case 24576: // S_IFBLK
return InternalTypeFlag.BLOCK_DEV;
case 8192: // S_IFCHR
return InternalTypeFlag.CHAR_DEV;
case 16384: // S_IFDIR
return TarTypeFlag.DIRECTORY;
case 4096: // S_IFIFO
return InternalTypeFlag.FIFO;
case 40960: // S_IFLNK
return TarTypeFlag.SYMLINK;
default:
return TarTypeFlag.FILE;
}
}
function encodeString(
target: Uint8Array,
from: number,
to: number,
value: string | null | undefined
) {
if (value) ENCODER.encodeInto(`${value}\0`, target.subarray(from, to));
}
function encodeOctal(
target: Uint8Array,
from: number,
to: number,
value: number
) {
const length = to - from;
const max = length <= 8 ? 0o7777777 : 0o77777777777;
if (value > max) {
target[from] = 0x80;
let num = value;
for (let idx = to - 1; idx > from; num = Math.floor(num / 0x100), idx--)
target[idx] = num & 0xff;
} else if (value < 0) {
target[from] = 0xff;
let num = -value;
let flipped = false;
for (let idx = to - 1; idx > from; num = Math.floor(num / 0x100), idx--) {
const byte = num & 0xff;
target[idx] = flipped
? (0xff ^ byte) & 0xff // ones comp
: ((0xff ^ byte) + 1) & 0xff; // twos comp
flipped ||= byte !== 0;
}
} else if (value) {
const octal = Math.floor(value).toString(8);
const pad = length - octal.length - 2;
const out = pad >= 0 ? `${'0'.repeat(pad)}${octal} ` : octal;
encodeString(target, from, to, out);
}
}
function encodeChecksum(bytes: Uint8Array) {
let sum = CHECKSUM_INITIAL;
for (let idx = 0; idx < 148; idx++) sum += bytes[idx];
for (let idx = 156; idx < 512; idx++) sum += bytes[idx];
encodeOctal(bytes, 148, 156, sum);
}
// Needed if a path is longer than 100 characters
// It attempts to split the path at a slash into a prefix and name
// The prefix capacity is 155 and the name is 100
function indexOfPrefixEnd(path: string): number {
if (path.length <= 255) {
let idx = path.length - 1;
while ((idx = path.lastIndexOf('/', idx - 1)) > -1) {
const prefixLen = idx;
const nameLen = path.length - idx - 1;
if (prefixLen < MAX_PREFIX_LEN && nameLen < MAX_NAME_LEN) return idx;
}
}
return -1;
}
function encodeBase(target: Uint8Array, header: TarHeader): 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 |
*/
let name = header.name;
if (!header._paxName && !header._longName && name.length > MAX_NAME_LEN) {
const idx = indexOfPrefixEnd(name);
if (idx > -1) {
name = name.slice(idx + 1);
}
}
if (!header.typeflag) header.typeflag = modeToType(header.mode);
if (!header.mode)
header.mode = header.typeflag === TarTypeFlag.DIRECTORY ? 0o755 : 0o644;
if (!header.mtime) header.mtime = Math.floor(new Date().valueOf() / 1000);
encodeString(target, 0, 100, name);
encodeOctal(target, 100, 108, header.mode & 0o7777);
encodeOctal(target, 108, 116, header.uid);
encodeOctal(target, 116, 124, header.gid);
encodeOctal(target, 124, 136, header.size);
encodeOctal(target, 136, 148, header.mtime);
// CHECKSUM: 148 - 156
target[156] = header.typeflag;
encodeString(target, 157, 257, header.linkname);
encodeString(target, 257, 265, MAGIC); // TMAGIC + TVERSION
encodeString(target, 265, 297, header.uname);
encodeString(target, 297, 329, header.gname);
encodeOctal(target, 329, 337, header.devmajor);
encodeOctal(target, 337, 345, header.devminor);
encodeString(target, 345, 500, header._prefix);
encodeChecksum(target);
}
function encodeHeader(header: TarHeader): Uint8Array<ArrayBuffer> {
const block = new Uint8Array(BLOCK_SIZE);
encodeBase(block, header);
return block;
}
function encodePax(header: TarHeader): Uint8Array<ArrayBuffer> | null {
function encodePaxEntry(key: string, value: string) {
const line = ` ${key}=${value}\n`;
let length = line.length;
const prefix = `${length}`;
length += prefix.length;
// Since the encoded length must include the digits of length itself, we have to make
// sure we roll over the total number of characters using log10
if (1 + Math.floor(Math.log10(length)) > prefix.length) length += 1;
return `${length}${line}`;
}
let output = '';
if (header._paxName) output += encodePaxEntry('path', header._paxName);
if (header._paxLinkName)
output += encodePaxEntry('linkpath', header._paxLinkName);
return output ? ENCODER.encode(output) : null;
}
function paxName(name: string) {
const idx = name.lastIndexOf('/');
const basename = idx > -1 ? name.slice(idx) : name;
return `PaxHeader/${basename.slice(-99)}`;
}
export async function* tar(
entries: ReadableStreamLike<TarChunk | TarFile>
): AsyncGenerator<Uint8Array<ArrayBuffer>> {
const next = streamLikeToIterator(entries);
let result: Awaited<ReturnType<typeof next>>;
while (!(result = await next()).done && result.value) {
const { value: entry } = result;
const header = initTarHeader(entry);
if (!Number.isSafeInteger(header.size) || header.size < 0) {
throw new Error(
`Invalid Tar: Cannot safely encode part with size ${header.size}`
);
}
if (entry.lastModified && !header.mtime)
header.mtime = Math.floor(entry.lastModified / 1000);
if (
header.typeflag === TarTypeFlag.DIRECTORY &&
!header.name.endsWith('/')
) {
header.name += '/';
} else if (header.typeflag === TarTypeFlag.SYMLINK) {
header.size = 0;
}
if (header.name.length > MAX_NAME_LEN) {
const idx = indexOfPrefixEnd(header.name);
if (idx > -1) {
header._prefix = header.name.slice(0, idx);
header.name = header.name.slice(idx + 1);
} else {
header._paxName = header.name;
header.name = paxName(header.name);
}
}
if (header.linkname && header.linkname.length > MAX_NAME_LEN) {
header._paxLinkName = header.linkname;
header.linkname = paxName(header.name);
}
const pax = encodePax(header);
if (pax) {
const paxHeader = initTarHeader(null);
paxHeader.typeflag = InternalTypeFlag.PAX;
paxHeader.size = pax.byteLength;
yield encodeHeader(paxHeader);
yield pax;
const pad = blockPad(pax.byteLength);
if (pad) yield new Uint8Array(pad);
}
yield encodeHeader(header);
const stream = entry.stream();
if (header.size) {
yield* streamToIterator(stream);
} else if (!stream.locked) {
await stream.cancel();
}
const pad = blockPad(entry.size);
if (pad) yield new Uint8Array(pad);
}
yield new Uint8Array(BLOCK_SIZE * 2);
}