code: public RecordReader<Text, Text> getRecordReader( InputSplit genericSplit, 
                                                     JobConf job,
                                                     Reporter reporter)
      throws IOException 
      {
        reporter.setStatus(genericSplit.toString());
        
        FileSplit split = (FileSplit) genericSplit;
        final Path file  = split.getPath();
        
        return new RecordReader<Text,Text>()
          {
            boolean done = false; 
  
            public void close() 
            { 
            }
            
            public Text createKey() 
            {
              return new Text();
            }
  
            public Text createValue() 
            { 
              return new Text();
            }
  
            public long getPos() 
            { 
              return 0;
            }
            
            public float getProgress() 
            { 
              return 0.0f;
            }
            
            public boolean next( Text key, Text value) 
            { 
              if ( done ) return false;
  
              key  .set( file.toString() );
              value.set( file.toString() );
  
              done = true ;
  
              return true;
            }
  
          };
      }
docs: Return a RecordReader which returns 1 record: the file path from
  the InputSplit.