RFR: 8329995: Restricted access to `/proc` can cause JFR initialization to crash [v2]

[David Holmes]

On Mon, 15 Apr 2024 13:21:01 GMT, Jaroslav Bachorik <jbachorik at openjdk.org> wrote:

>> Please, review this trivial change to make using `ProcessIterator` more robust in the presence of SELinux or a similar system.
>> 
>> The call to `os::opendir("/proc")` may return `nulltptr` if the `/proc` is not accessible due to restrictions placed by the SELinux. In that case the `ProcessIterator` will SIGSEG because it assumes the `_dir`, which is the variable storing the result  of the `os::opendir("/proc")` call to be non-null.
>> 
>> The patch is missing regression test because it is very hard to simulate `/proc` not being accessible to the test process.
>
> Jaroslav Bachorik has updated the pull request incrementally with one additional commit since the last revision:
> 
>   Add explanatory comment

@jbachorik  - apologies I have been away a bit lately.

I can't quite convince myself that we may not have problems accessing /proc elsewhere because in a few places the path is constructed in one part of the code and then used somewhere else. But that is not the concern of this PR which is fixing a specific observed problem.

Thanks

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Marked as reviewed by dholmes (Reviewer).

PR Review: https://git.openjdk.org/jdk/pull/18775#pullrequestreview-2016264553