}
	return err
}

var (
	compressors   sync.Map // map[uint16]Compressor
	decompressors sync.Map // map[uint16]Decompressor
)

func init() {
	compressors.Store(Store, Compressor(func(w io.Writer) (io.WriteCloser, error) { return &nopCloser{w}, nil }))
	compressors.Store(Deflate, Compressor(func(w io.Writer) (io.WriteCloser, error) { return newFlateWriter(w), nil }))

	decompressors.Store(Store, Decompressor(io.NopCloser))

}

// RegisterCompressor registers or overrides a custom compressor for a specific
// method ID. If a compressor for a given method is not found, [Writer] will
// default to looking up the compressor at the package level.
func (w *Writer) RegisterCompressor(method uint16, comp Compressor) {
	if w.compressors == nil {
		w.compressors = make(map[uint16]Compressor)
	}
	w.compressors[method] = comp
}

		return sealETag(key, md5sumcurr)
	}
	return fn
}

// compressOpts are the options for writing compressed data.
var compressOpts []s2.WriterOption

func init() {
	if runtime.GOARCH == "amd64" {
		// On amd64 we have assembly and can use stronger compression.
		compressOpts = append(compressOpts, s2.WriterBetterCompression())
	}
}

func (r *Reader) RegisterDecompressor(method uint16, dcomp Decompressor) {
	if r.decompressors == nil {
		r.decompressors = make(map[uint16]Decompressor)
	}
	r.decompressors[method] = dcomp
}

func (r *Reader) decompressor(method uint16) Decompressor {
	dcomp := r.decompressors[method]
	if dcomp == nil {
		dcomp = decompressor(method)
	}
	return dcomp
}

Such objects do not produce efficient [`LZ compression`](https://en.wikipedia.org/wiki/LZ77_and_LZ78)
which is a fitness factor for a lossless data compression.

Pre-compressed input typically compresses in excess of 2GiB/s per core,
so performance impact should be minimal even if precompressed data is re-compressed.
Decompressing incompressible data has no significant performance impact.

			s3Select.progressReader.Close()

			var stErr bzip2.StructuralError
			if errors.As(err, &stErr) {
				return errInvalidCompression(err, s3Select.Input.CompressionType)
			}
			// Test these compressor errors
			errs := []error{
				gzip.ErrHeader, gzip.ErrChecksum,
				s2.ErrCorrupt, s2.ErrUnsupported, s2.ErrCRC,

//			log.Fatal(err)
//		}
//		if err := w.Close(); err != nil {
//			log.Fatal(err)
//		}
//		return buf.Bytes()
//	}
//
// The 4 GB of zeros compresses to 4 MB, which compresses to 20 kB,
// which compresses to 1252 bytes (in the hex dump below).
//
// It's here in hex for the same reason as rZipBytes above: to avoid
// problems with on-disk virus scanners or other zip processors.