Re: [patch]spawn-pipe.c / spawni.c compile on OpenVMS.

[John E. Malmberg]

On 7/3/2017 7:26 PM, Bruno Haible wrote:
> John E. Malmberg wrote:
> > For Bash and Coreutils, I have a close to a pipe replacement that uses a
> > slightly different API in that you have to know if the pipe is parent to
> > child or child to parent when you create the pipes.  This handles pipes
> > up to the amount of virtual memory available to the process.
>
> You mean, such an implementation will not be usable for the case when
>    1. parent process calls pipe()
>    2. parent process forks child process 1,
>    3. parent process forks child process 2,
>    4. parent closes its copies of the fds from the pipe() call
> because in this case the communication happens between two sibling processes?

Pretty much.  I had not considered that case because I did not need it 
for Bash.

Since OpenVMS has to vfork()/exec() children and not just fork() them, 
specifying the fds to the child can also have its own special fun so 
porting such a pattern might not be simple.

> I agree that many uses of pipe() are for parent-child communication.
> Does someone know how frequent the use of pipe() for sibling processes is?

Not me.

Regards,
-John