Re: [PATCH 2/3] posix: Use posix_spawn on popen

[Adhemerval Zanella <adhemerval dot zanella at linaro dot org>]

On 18/09/2018 22:17, Rich Felker wrote:
> On Tue, Sep 18, 2018 at 02:01:29PM -0400, Zack Weinberg wrote:
>> On Sun, Sep 16, 2018 at 1:13 AM David Newall <glibc@davidnewall.com> wrote:
>>> It seems to me that there are still reasonable questions about whether
>>> to use posix_spawn or vfork ("posix_spawn is a badly designed API").
>>
>> When I said to Sergey that I would rather see the problem they
>> reported addressed using vfork instead of posix_spawn, I was giving
>> advice to a new contributor.  I really _would_ rather see it addressed
>> that way, and I also thought that they were more likely to succeed in
>> writing those patches.
>>
>> Adhemerval is not a new contributor and they deeply understand the
>> problems in this area.  Their patches strike me as a step generally in
>> the right direction.  I don't have time to review them in detail, but
>> I don't object to them.  However, do I think some of the fine details
>> demonstrate why an API that allows for arbitrary computation and
>> system calls before exec would be preferable, such as there being "no
>> safe way to clear close-on-exec in the child" (because, IIUC, there's
>> no posix_spawn action to do that).
> 
> The resolution to Austin Group issue #411 made it so adddup2(n,n) does
> what you want:
> 
> http://austingroupbugs.net/view.php?id=411

I has been tracked on https://sourceware.org/bugzilla/show_bug.cgi?id=23640 
as well. I am not found of having adddup2(n,n) semantic different dup2(n,n),
but I don't have a better straightforward solution either.