RFR: 8294193: Files.createDirectories throws FileAlreadyExistsException for a symbolic link whose target is an existing directory

[Jaikiran Pai]

On Thu, 22 Sep 2022 06:34:53 GMT, Jaikiran Pai <jpai at openjdk.org> wrote:

> Can I please get a review of this change which proposes to fix the issue noted in https://bugs.openjdk.org/browse/JDK-8294193?
> 
> As discussed in a related PR https://github.com/openjdk/jdk/pull/10266#issuecomment-1246800456, this is a genuine bug in the `java.nio.file.Files.createDirectories` implementation. The commit in this PR fixes that by making sure that links are followed when checking if a `Path` is a directory during the creation of directories in the `createDirectories` implementation. The `private` method which is changed in this PR is only used in the `Files.createDirectories` and no other place, so this change should not impact any other code. Additionally a new test has been added to reproduce the issue and verify the fix.
> tier1, tier2 and tier3 tests passed with this change.

Hello Alan,

> I think create a new issue for Files.createDirectories issue or else move the existing issue from hotspot/runtime and change the description.

I've now created a separate JBS and this PR has been updated to link to that JBS.

> For the test then I think it will mean moving the existing tests from Misc.java to the new source file. That will fit with the description that you propose for the new test.

I've updated the PR to move the `Files.createDirectories` testing from `Misc.java` to this new test class. I have done some trivial cosmetic/non-functional changes to this moved test (things like printing an assert message if/when any assertion fails in that test).

> I plan to review this change but not today because it require digging into some security issues.

Please take your time.

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PR: https://git.openjdk.org/jdk/pull/10383