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Date: Fri, 7 Jul 2017 17:04:02 +0200
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Subject: Re: [PHP-DEV] Getting fd from stream
From: php@list.imperialat.at (Martijn van Duren)

On 07/07/17 16:38, Sara Golemon wrote:
> On Fri, Jul 7, 2017 at 10:04 AM, Martijn van Duren
> <php@list.imperialat.at> wrote:
>> My use case is to set up a cluster of processes each with their own task
>> and permission sets. These processes need to be able to communicate with
>> each other over socket pairs, not just between the parent and the child,
>> but also between children.
>>
> Sounds like you're describing unix domain sockets (or NamedPipes if
> you're on Windows).
> 
> -Sara
> 
Yes, although tcp/ip are also possible with stream_socket_pair.

The point is, regardless of unix - or tcp sockets, they still have an
underlying file descriptor, which I need to specify to the child, so
that they can start using it. Ergo, I need to find a way to export this
from the stream into PHP.

To put it in code:
<?php
$sp = stream_socket_pair(STREAM_PF_UNIX, STREAM_SOCK_STREAM, 0);
echo (int) $sp[0]."\n";
?>

This returns 4 (the object id), instead of 3 (the fd).

If I could get the fd, I could turn this into something like:

<?php
$sp = stream_socket_pair(STREAM_PF_UNIX, STREAM_SOCK_STREAM, 0);
switch (pcntl_fork()) {
case -1:
	exit(255);
case 0:
	fclose($sp[1]);
	pcntl_exec("/usr/local/libexec/whatever", ["-i", (int) $sp[0]]);
default:
	fclose($sp[0]);
	do_parent_code();
}
?>

Where whatever can be anything from a PHP-script to a C-compiled binary.