[Hadoop-common-dev] map reduce permission

Hi,
To get supergroup's file access mode is possible in map&reduce class.
I wrote a code like this

class MyMap implements Mapper {
public void map(...) {
Configuration conf = new Configuration();
FileSystem fs = FileSystem.get(conf);
fs.open(new Path("/user/supergroup_user/file_name");
}
}

If no "hadoop.job.ugi" property in configuration, UserGroupInformation class
uses linux user(run shell command "whoami").