can1357/oh-my-pi · error · ArchiveError

Invalid ${label} command Huffman table

Error message

Invalid ${label} command Huffman table

What it means

readCommandTree decodes the per-block command Huffman code-length table. When a run-length skip entry (code 0/1/2) would skip past the declared number of encoded symbols, the table is corrupt or misaligned, so the library refuses to build it.

Source

Thrown at packages/utils/src/ar/lzh.ts:172

			if (index + skipped > encodedCount) throw new ArchiveError(`Invalid ${label} temporary Huffman table`);
			index += skipped;
		}
	}
	return CanonicalHuffman.build(lengths, symbolCount, label);
}

function readCommandTree(reader: MsbBitReader, temporary: CanonicalHuffman, label: string): CanonicalHuffman {
	const symbolCount = 510;
	const encodedCount = reader.read(9);
	if (encodedCount === 0) return CanonicalHuffman.single(reader.read(9), symbolCount, label);
	if (encodedCount > symbolCount) throw new ArchiveError(`Invalid ${label} command Huffman table size`);
	const lengths = new Uint8Array(symbolCount);
	let index = 0;
	while (index < encodedCount) {
		const code = temporary.decode(reader);
		if (code <= 2) {
			const skipped = code === 0 ? 1 : code === 1 ? reader.read(4) + 3 : reader.read(9) + 20;
			if (index + skipped > encodedCount) throw new ArchiveError(`Invalid ${label} command Huffman table`);
			index += skipped;
		} else {
			lengths[index++] = code - 2;
		}
	}
	return CanonicalHuffman.build(lengths, symbolCount, label);
}

function readPositionTree(
	reader: MsbBitReader,
	positionBits: number,
	symbolCount: number,
	label: string,
): CanonicalHuffman {
	const encodedCount = reader.read(positionBits);
	if (encodedCount === 0) return CanonicalHuffman.single(reader.read(positionBits), symbolCount, label);
	if (encodedCount > symbolCount) throw new ArchiveError(`Invalid ${label} position Huffman table size`);
	const lengths = new Uint8Array(symbolCount);

View on GitHub (pinned to 9690622007)

Solutions

1. Re-obtain or re-extract the archive; verify checksum/CRC of the source file
2. Confirm the correct method/positionBits/positionSymbols parameters for the archive variant being decoded
3. Check that decompression starts exactly at the compressed-data offset (extended headers consumed correctly)
4. If the input is untrusted, expect and handle ArchiveError rather than treating it as a bug

Example fix

// before
try { out = decompressLhStatic(packed, outSize, 5, 256, "LZH -lh5-"); }
catch (e) { /* crash */ }
// after
try {
  out = decompressLhStatic(packed, outSize, 5, 256, "LZH -lh5-");
} catch (e) {
  if (e instanceof ArchiveError) {
    console.error("Archive corrupt or unsupported variant:", e.message);
    out = null;
  } else throw e;
}

// Can't pre-validate Huffman tables without decoding; at minimum sanity-check input
if (packed.length === 0 || outSize <= 0) throw new Error("bad decompress inputs");

try {
  const out = decompressLhStatic(packed, outSize, positionBits, positionSymbols, label);
} catch (err) {
  if (err instanceof ArchiveError) return null; // treat member as corrupt
  throw err;
}

When it happens

Trigger: Calling decompressLhStatic (via the LZH/ARJ read APIs) on a stream whose 16-bit block header or code-length table bits are corrupt, truncated-and-resumed, or whose bit reader is misaligned because an earlier field was parsed at the wrong offset.

Common situations: Corrupted archives from failed downloads or bad media; hand-crafted/fuzzed archives; using the wrong method label/dictionary size for a variant (e.g. ARJ method 1-3 vs -lh5-..-lh7-), which shifts bit boundaries.

Related errors

• Invalid ${label} Huffman table: oversubscribed codes
• Invalid ${label} Huffman table: incomplete codes
• Invalid ${label} Huffman table: prefix collision
• Invalid ${label} Huffman table: duplicate code
• Invalid ${this.#label} Huffman code

AI-assisted analysis of can1357/oh-my-pi@9690622007 (2026-08-31). Data as JSON: /api/errors/9f589e0593561e3c. Report an issue: GitHub.