@Override
  public FSDataInputStream open(Path upperPath, int bufferSize) throws IOException {
    SfsInfo info = new SfsInfo(upperPath);
    switch (info.type) {
    case LEAF_FILE:
      return info.lowerTargetPath.getFileSystem(conf).open(info.lowerTargetPath, bufferSize);
    case NONEXISTENT:
      throw newFileNotFoundException(upperPath.toString());
    default:
      throw unsupported("open:" + upperPath);
    }
  }
Implements an abstraction layer to show files in a single directory.

Suppose the filesystem has a directory in which there are multiple files:
file://somedir/f1.txt
file://somedir/f2.txt

In case of Hive the content of a directory may be inside a table.
To give a way to show a single file as a single file in a directory it could be specified:

sfs+file://somedir/f1.txt/#SINGLEFILE#

This will be a directory containing only the f1.txt and nothing else.
ql/src/java/org/apache/hadoop/hive/ql/io/SingleFileSystem.java