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https://issues.apache.org/jira/browse/HADOOP-8731?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13455024#comment-13455024
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Bikas Saha commented on HADOOP-8731:
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Looks like the chmod fixes an existing generic bug.
Can you please clarify the following scenario so that other folks reading this
thread have it easy?
Directory A (perm for user Foo) contains directory B (perm for Everyone)
So contents of A will be private cache and contents of B will be public cache
on Windows but not on Linux.
> Public distributed cache support for Windows
> --------------------------------------------
>
> Key: HADOOP-8731
> URL: https://issues.apache.org/jira/browse/HADOOP-8731
> Project: Hadoop Common
> Issue Type: Bug
> Components: filecache
> Reporter: Ivan Mitic
> Assignee: Ivan Mitic
> Attachments: HADOOP-8731-PublicCache.patch
>
>
> A distributed cache file is considered public (sharable between MR jobs) if
> OTHER has read permissions on the file and +x permissions all the way up in
> the folder hierarchy. By default, Windows permissions are mapped to "700" all
> the way up to the drive letter, and it is unreasonable to ask users to change
> the permission on the whole drive to make the file public. IOW, it is hardly
> possible to have public distributed cache on Windows.
> To enable the scenario and make it more "Windows friendly", the criteria on
> when a file is considered public should be relaxed. One proposal is to check
> whether the user has given EVERYONE group permission on the file only (and
> discard the +x check on parent folders).
> Security considerations for the proposal: Default permissions on Unix
> platforms are usually "775" or "755" meaning that OTHER users can read and
> list folders by default. What this also means is that Hadoop users have to
> explicitly make the files private in order to make them private in the
> cluster (please correct me if this is not the case in real life!). On
> Windows, default permissions are "700". This means that by default all files
> are private. In the new model, if users want to make them public, they have
> to explicitly add EVERYONE group permissions on the file.
> TestTrackerDistributedCacheManager fails because of this issue.
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