Function checkHeader

internal/compression/compression.go:87–97

CheckHeader checks whether the first bytes from a PeekReader match an expected header

(pr PeekReader, expectedHeader []byte)

// CheckHeader checks whether the first bytes from a PeekReader match an expected header
func checkHeader(pr PeekReader, expectedHeader []byte) (bool, PeekReader, error) {
	header, err := pr.Peek(len(expectedHeader))
	if err != nil {
		// https://github.com/google/go-containerregistry/issues/367
		if err == io.EOF {
			return false, pr, nil
		}
		return false, pr, err
	}
	return bytes.Equal(header, expectedHeader), pr, nil
}