Review request for 5049299

[Michael McMahon]

Florian Weimer wrote:
> * Michael McMahon:
>
>   
>> webrev location: http://cr.openjdk.java.net/~michaelm/5049299/webrev.00/
>>
>> **I'd like to give an outline of the change here, to make reviewing
>> the webrev a bit easier.  Basically, while posix_spawn() is a fairly
>> elaborate and complicated system call, it can't quite do everything
>> that the old fork()/exec() combination can do,
>>     
>
> I've always assumed that the ProcessBuilder requirements could be
> fulfilled by posix_spawn and friends.  Could you elaborate why this is
> not the case?
>
>   
> The file descriptor setup race mentioned in the comments shouldn't
> apply, really--the reshuffling should occur in the child, isolated
> from the parent, otherwise the implementation is quite broken and
> pointless.
>
>   
But you can't expect an arbitrary command (eg. "/bin/ls") to do any
"reshuffling". It has to be done by something
in between the parent and the target command.

The other problem, is the requirement to change working directory
for the target. posix_spawn() doesn't allow this.

Just to be clear as well, posix_spawn() is being used (to avoid
the fork() memory duplication issue) but it isn't able to complete
the job which is why we need this extra helper (on Solaris).

Thanks,
Michael.