[jdk17u-dev] RFR: 8329995: Restricted access to `/proc` can cause JFR initialization to crash [v2]

[Neethu Prasad]

> Backport of JDK-8329995
> 
> 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.
> 
> **Testing**
> All jdk_jfr and hotspot_gc tests passed.

Neethu Prasad has updated the pull request incrementally with one additional commit since the last revision:

  8329995: Address PR feedback to remove extra ; and use NULL instead of nullptr

-------------

Changes:
  - all: https://git.openjdk.org/jdk17u-dev/pull/2516/files
  - new: https://git.openjdk.org/jdk17u-dev/pull/2516/files/8691b3dc..67d58536

Webrevs:
 - full: https://webrevs.openjdk.org/?repo=jdk17u-dev&pr=2516&range=01
 - incr: https://webrevs.openjdk.org/?repo=jdk17u-dev&pr=2516&range=00-01

  Stats: 1 line in 1 file changed: 0 ins; 0 del; 1 mod
  Patch: https://git.openjdk.org/jdk17u-dev/pull/2516.diff
  Fetch: git fetch https://git.openjdk.org/jdk17u-dev.git pull/2516/head:pull/2516

PR: https://git.openjdk.org/jdk17u-dev/pull/2516