JuliusBrussee/caveman · error

invalid decompression limit %d

Error message

invalid decompression limit %d

What it means

DecompressLimit rejects a maxBytes ceiling that is negative or above the DefaultMaxDecompressedBytes cap (128 MiB). The at-fault input is the caller-supplied limit itself: callers with trusted metadata may lower the bound but may not raise it past the defensive default, preventing a caller from accidentally disabling the decompression-bomb protection.

Source

Thrown at shared/platform/objectstore/compress.go:68

		return zstdEnc.EncodeAll(data, nil), nil
	default:
		return nil, fmt.Errorf("unknown compression codec %q", codec)
	}
}

// Decompress reverses Compress with a defensive default expansion ceiling. An
// unknown codec fails closed.
func Decompress(codec string, data []byte) ([]byte, error) {
	return DecompressLimit(codec, data, DefaultMaxDecompressedBytes)
}

// DecompressLimit reverses Compress while refusing to produce more than
// maxBytes of plaintext. The limit is applied while decoding gzip and through
// zstd's decoder memory bound, so highly-compressible hostile payloads cannot
// first allocate their full expanded size and only then be rejected.
func DecompressLimit(codec string, data []byte, maxBytes int64) ([]byte, error) {
	if maxBytes < 0 || maxBytes > DefaultMaxDecompressedBytes {
		return nil, fmt.Errorf("invalid decompression limit %d", maxBytes)
	}
	switch codec {
	case CompressionNone, "":
		if int64(len(data)) > maxBytes {
			return nil, ErrDecompressedTooLarge
		}
		return data, nil
	case CompressionGzip:
		zr, err := gzip.NewReader(bytes.NewReader(data))
		if err != nil {
			return nil, fmt.Errorf("gzip reader: %w", err)
		}
		defer zr.Close()
		out, err := io.ReadAll(io.LimitReader(zr, maxBytes+1))
		if err != nil {
			return nil, fmt.Errorf("gzip read: %w", err)
		}
		if int64(len(out)) > maxBytes {

View on GitHub (pinned to 766dce6b13)

Solutions

1. Pass a limit between 0 and DefaultMaxDecompressedBytes (128 MiB)
2. Use Decompress (no explicit limit) if the default ceiling is what you want
3. Fix the size-metadata source that produced a negative or oversized limit value

When it happens

Trigger: Thrown at shared/platform/objectstore/compress.go:68 when the library encounters an invalid state.

Common situations: See trigger scenarios.

AI-assisted analysis of JuliusBrussee/caveman@766dce6b13 (2026-08-18). Data as JSON: /api/errors/dbc2fd7e5aa22f3d. Report an issue: GitHub.