[jira] [Commented] (HDFS-2956) calling fetchdt without a --renewer argument throws NPE

["Aaron T. Myers (JIRA)" <ji...@apache.org>]

    [ https://issues.apache.org/jira/browse/HDFS-2956?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13784843#comment-13784843 ] 

Aaron T. Myers commented on HDFS-2956:
--------------------------------------

You actually can't safely downgrade a PB field from required to optional in a compatible fashion. If you did so, the side trying to deserialize a message that still has the field marked "required" will consider a message missing this field to be a malformed message. See the section on [this page|https://developers.google.com/protocol-buffers/docs/proto] entitled "Required is Forever."

> calling fetchdt without a --renewer argument throws NPE
> -------------------------------------------------------
>
>                 Key: HDFS-2956
>                 URL: https://issues.apache.org/jira/browse/HDFS-2956
>             Project: Hadoop HDFS
>          Issue Type: Bug
>          Components: security
>    Affects Versions: 0.24.0, 3.0.0
>            Reporter: Todd Lipcon
>            Assignee: Vinay
>         Attachments: HDFS-2956.patch
>
>
> If I call "bin/hdfs fetchdt /tmp/mytoken" without a "--renewer foo" argument, then it will throw a NullPointerException:
> Exception in thread "main" java.lang.NullPointerException
>         at org.apache.hadoop.hdfs.protocolPB.ClientNamenodeProtocolTranslatorPB.getDelegationToken(ClientNamenodeProtocolTranslatorPB.java:830)
> this is because getDelegationToken is being called with a null renewer



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