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https://issues.apache.org/jira/browse/HADOOP-9912?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13773027#comment-13773027
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Jason Lowe commented on HADOOP-9912:
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bq. Another crazy thought I'd like to throw out - what if we just returned
false for isDir if we cannot resolve the symlink rather than throw an exception?
This sounds equivalent to the earlier proposal where "bad" symlinks are
returned as the raw symlink. isDir() and isFile() both return false for
symlinks, and old clients are not aware of isFile() since it was added with
symlink support.
An old client of listStatus will interpret the link as a file since isDir() is
false, but we don't know if that's the proper thing to do since we don't know
the client's intent. If a directory walker is concerned about directories and
not files at some point in the traverse, it could end up silently skipping a
"bad" symlink when it should have failed. i.e.: symlink to directory in remote
filesystem but filesystem is temporarily unavailable, symlink to directory in
permission-protected tree, symlink intended to point to a directory but typo'd
the target when link was created, etc.
I'm not sure how common that case really is in practice. Our recent proposal
is trying to err on the side of caution so we don't accidentally drop data when
we should have failed. It does mean some scenarios for old clients will fail
when they should have succeeded despite "bad" symlinks, but it seems better to
report a failure that can be corrected (i.e.: fix the "bad" symlink and re-run
the app) than to potentially skip desired inputs.
> globStatus of a symlink to a directory does not report symlink as a directory
> -----------------------------------------------------------------------------
>
> Key: HADOOP-9912
> URL: https://issues.apache.org/jira/browse/HADOOP-9912
> Project: Hadoop Common
> Issue Type: Bug
> Components: fs
> Affects Versions: 2.1.0-beta
> Reporter: Jason Lowe
> Priority: Blocker
> Attachments: HADOOP-9912-testcase.patch, new-hdfs.txt, new-local.txt,
> old-hdfs.txt, old-local.txt
>
>
> globStatus for a path that is a symlink to a directory used to report the
> resulting FileStatus as a directory but recently this has changed.
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