import java.nio.channels.FileChannel;

svoid truncateFile(S path, long size) {
  truncateFile(newFile(path), size);
}

svoid truncateFile(File f, long size) ctex {
  FileChannel outChan = newFileOutputStream(f, true).getChannel();
  try {
    outChan.truncate(size);
  } finally {
    outChan.close();
  }
}