RFR(s): (new approach) 8223777: In posix_spawn mode, failing to exec() jspawnhelper does not result in an error

[Florian Weimer]

* Thomas Stüfe:

> Hi all,
>
> (old mail thread: https://mail.openjdk.java.net/pipermail/core-libs-dev/2019-May/060139.html)
>
> May I please have your reviews and opinions for the following bug fix:
>
> issue: https://bugs.openjdk.java.net/browse/JDK-8223777
> cr: http://cr.openjdk.java.net/~stuefe/webrevs/8223777-posix_spawn-no-exec-error-alternate-impl/webrev.00/webrev/
>
> ---

I wonder if you should use 0 as the value for CHILD_IS_ALIVE.  All
integers could be valid errno values.  But if you check for errors from
the restartableWrite call (and call _exit), I don't think there is a
risk of confusion, so the value does not have to be distinct.

Thanks,
Florian