RFR: 8179887 - Build failure with glibc >= 2.24: error: 'int readdir_r(DIR*, dirent*, dirent**)' is deprecated

[Kim Barrett]

> On Apr 23, 2018, at 3:51 AM, Michal Vala <mvala at redhat.com> wrote:
> 
> Hi,
> 
> following discussion "RFR: build pragma error with gcc 4.4.7"[1], I'm posting updated patch replacing deprecated readdir_r with readdir. Bug ID is JDK-8179887 [2].
> 
> webrev: http://cr.openjdk.java.net/~andrew/8179887/webrev/
> 
> I'm asking for the review and eventually sponsorship.

The change to os::readdir in os_linux.inline.hpp looks fine.

I was going to suggest that rather than changing perfMemory_linux.cpp to use os::readdir in an
unusual and platform-specific way, it should instead just call ::readdir directly.  However, neither
of those is right, and that part of the change should not be made; see
https://bugs.openjdk.java.net/browse/JDK-8134540
Much nearly duplicated code for PerfMemory support

Looking a bit deeper, there might be some additional follow-on that could be done, eliminating
the second argument to os::readdir.
windows: unused
bsd: freebsd also deprecated readdir_r, I think for similar reasons.
solaris: doc is clear about thread safety issue being about sharing the DIR*
aix: I haven’t looked at it, but would guess it’s similar.

In other words, don’t operate on the DIR* from multiple threads simultaneously, and just use
::readdir on non-Windows.  That would all be for another RFE though.