can1357/oh-my-pi · error · ArchiveError

Invalid CPIO archive: truncated ${what}

Error message

Invalid CPIO archive: truncated ${what}

What it means

requireRange validates that a requested byte range [start,end) lies within the CPIO buffer; when it does not, the archive is reported as 'truncated <what>' (which field, e.g. 'ino field' or 'magic field'). It is the bounds-check used while parsing header fields and entries, so any header that runs past EOF produces this error.

Source

Thrown at packages/utils/src/ar/cpio.ts:100

	let checksum = 0;
	for (const byte of bytes) checksum = (checksum + byte) >>> 0;
	return checksum;
}

function align(value: number, alignment: number): number {
	const remainder = value % alignment;
	return remainder === 0 ? value : value + alignment - remainder;
}

function requireRange(bytes: Uint8Array, start: number, end: number, what: string): void {
	if (
		!Number.isSafeInteger(start) ||
		!Number.isSafeInteger(end) ||
		start < 0 ||
		end < start ||
		end > bytes.byteLength
	) {
		throw new ArchiveError(`Invalid CPIO archive: truncated ${what}`);
	}
}

function parseDigits(bytes: Uint8Array, offset: number, length: number, radix: 8 | 16, field: string): number {
	requireRange(bytes, offset, offset + length, `${field} field`);
	let value = 0;
	for (let index = offset; index < offset + length; index++) {
		const code = bytes[index]!;
		let digit: number;
		if (code >= 0x30 && code <= 0x39) digit = code - 0x30;
		else if (radix === 16 && code >= 0x41 && code <= 0x46) digit = code - 0x41 + 10;
		else if (radix === 16 && code >= 0x61 && code <= 0x66) digit = code - 0x61 + 10;
		else throw new ArchiveError(`Invalid CPIO archive: ${field} is not a valid base-${radix} number`);
		if (digit >= radix) throw new ArchiveError(`Invalid CPIO archive: ${field} is not a valid base-${radix} number`);
		value = value * radix + digit;
	}
	if (!Number.isSafeInteger(value)) throw new ArchiveError(`Invalid CPIO archive: ${field} is too large`);
	return value;

View on GitHub (pinned to 9690622007)

Solutions

1. Re-acquire a complete archive and retry
2. Verify the cpio parses with the system tool: cpio -it < file
3. Check the offset/base you are parsing from if the cpio is embedded in a larger file
4. Confirm the format matches what the parser expects (odc vs newc)

Example fix

// before: wrong offset into container
const entries = await readCpioEntriesFromBuffer(container.subarray( guessedOffset ));
// after: locate the real cpio start (magic '070701' for newc)
const magicIndex = container.indexOf(Buffer.from('070701', 'ascii'));
const entries = await readCpioEntriesFromBuffer(container.subarray(magicIndex));

function looksLikeCpio(bytes: Uint8Array): boolean {
  const magic = Buffer.from(bytes.subarray(0, 6)).toString('ascii');
  return magic === '070701' || magic === '070702' || magic === '070707';
}
if (!looksLikeCpio(bytes) || bytes.byteLength < 110) throw new Error('not a (complete) cpio archive');

function looksLikeCpio(bytes: Uint8Array): boolean {
  const magic = Buffer.from(bytes.subarray(0, 6)).toString('ascii');
  return magic === '070701' || magic === '070702' || magic === '070707';
}

try {
  const entries = await readCpioEntriesFromBuffer(bytes);
} catch (err) {
  if (err instanceof ArchiveError && /^Invalid CPIO archive: truncated/.test(err.message)) {
    // message names which field ran past EOF; usually a truncated file or wrong offset
    throw new Error(`cpio unreadable (${err.message}); re-acquire or fix parse offset`);
  } else throw err;
}

When it happens

Trigger: Calling readCpioEntriesFromBuffer on truncated data; header fields extending past end-of-buffer due to a corrupted size/count field; parsing at a wrong offset inside a larger container so field reads run past the buffer end.

Common situations: Partial initramfs/cpio downloads; wrong offset when extracting a cpio embedded in a firmware image; format confusion (parsing an 'odc' file as 'newc' with wrong field widths); zero-length or empty cpio files.

Related errors

• CPIO member '${memberPath}' is truncated
• Invalid ARJ archive: truncated data
• Invalid CAB archive: member '${memberPath}' is outside its f
• Invalid XZ stream: truncated integer
• Invalid XZ stream: truncated variable-length integer

AI-assisted analysis of can1357/oh-my-pi@9690622007 (2026-08-31). Data as JSON: /api/errors/870f46bc80514c6e. Report an issue: GitHub.