presto-orc/src/main/java/io/prestosql/orc/metadata/OrcMetadataWriter.java/OrcMetadataWriter/writePostscript
class OrcMetadataWriter:    @Override
    public int writePostscript(SliceOutput output, int footerLength, int metadataLength, CompressionKind compression, int compressionBlockSize)
            throws IOException
    {
        OrcProto.PostScript postScriptProtobuf = OrcProto.PostScript.newBuilder()
                .addAllVersion(ORC_METADATA_VERSION)
                .setFooterLength(footerLength)
                .setMetadataLength(metadataLength)
                .setCompression(toCompression(compression))
                .setCompressionBlockSize(compressionBlockSize)
                .setWriterVersion(useLegacyVersion ? HIVE_LEGACY_WRITER_VERSION : PRESTO_WRITER_VERSION)
                .setMagic(MAGIC.toStringUtf8())
                .build();

        return writeProtobufObject(output, postScriptProtobuf);
    }