metadata: ByteString,
      bufferMaxSize: Long,
    ): Relay {
      val randomAccessFile = RandomAccessFile(file, "rw")
      val result = Relay(randomAccessFile, upstream, 0L, metadata, bufferMaxSize)

      // Write a dirty header. That way if we crash we won't attempt to recover this.
      randomAccessFile.setLength(0L)
      result.writeHeader(PREFIX_DIRTY, -1L, -1L)

      return result
    }

    assertTrue(Files.equal(asciiFile, temp));

    Files.copy(i18nFile, temp);
    assertTrue(Files.equal(i18nFile, temp));

    Files.copy(asciiFile, temp);
    RandomAccessFile rf = new RandomAccessFile(temp, "rw");
    rf.writeByte(0);
    rf.close();
    assertEquals(asciiFile.length(), temp.length());
    assertFalse(Files.equal(asciiFile, temp));

    assertTrue(Files.equal(asciiFile, temp));

    Files.copy(i18nFile, temp);
    assertTrue(Files.equal(i18nFile, temp));

    Files.copy(asciiFile, temp);
    RandomAccessFile rf = new RandomAccessFile(temp, "rw");
    rf.writeByte(0);
    rf.close();
    assertEquals(asciiFile.length(), temp.length());
    assertFalse(Files.equal(asciiFile, temp));

      throws IOException {
    checkNotNull(file);
    checkNotNull(mode);

    Closer closer = Closer.create();
    try {
      RandomAccessFile raf =
          closer.register(new RandomAccessFile(file, mode == MapMode.READ_ONLY ? "r" : "rw"));
      FileChannel channel = closer.register(raf.getChannel());
      return channel.map(mode, 0, size == -1 ? channel.size() : size);

      throws IOException {
    checkNotNull(file);
    checkNotNull(mode);

    Closer closer = Closer.create();
    try {
      RandomAccessFile raf =
          closer.register(new RandomAccessFile(file, mode == MapMode.READ_ONLY ? "r" : "rw"));
      FileChannel channel = closer.register(raf.getChannel());
      return channel.map(mode, 0, size == -1 ? channel.size() : size);