Overwrite all open file descriptors with /dev/null streams

[WyriHaximus]

This also gets rid of STD* streams so we can fully support windows again

Refs reactphp/child-process#65

[kelunik]

Does that work fine on OS X? I think there are portability issues with /proc/self for getting all open FDs IIRC. It also isn't a solution that works on Windows.

[WyriHaximus]

@kelunik I'm open for suggestions for windows and OS X 👍

[NanoSector]

Using /dev/fd seems to be the equivalent for /proc/self/fd on macOS.

[WyriHaximus]

This doesn't work either:

<?php

foreach (new DirectoryIterator('php://fd/*') as $i => $v) {
    var_export([$i, $v]);
}

Results in:

PHP Fatal error: Uncaught UnexpectedValueException: DirectoryIterator::__construct(php://fd/*): failed to open dir: not implemented in /home/wyrihaximus/Projects/php-file-descriptors/test.php:3

[kelunik]

I don't have suggestions, otherwise we would have a solution for Amp already. :-(

[WyriHaximus]

@kelunik would a RFC for something like new DirectoryIterator('php://fd/*') be doable?

[kelunik]

Not sure, I think php://fd is just a mapping. The correct solution would be defaulting every FD to CLOEXEC.

[WyriHaximus]

Not sure, I think php://fd is just a mapping.

Hmm ok, but is or isn't there an internal list of internal file descriptors?

The correct solution would be defaulting every FD to CLOEXEC.

Would that be hard or easy to do for 7.4 or 8.0? (That wouldn't help us right now, but having that the default in the future would be awesome.)

[kelunik]

There's a list of open resources, but not sure whether there's a list of open file descriptors (including inherited ones).

As PHP is single threaded, closing all resources on proc_open after forking might be good enough.

[WyriHaximus]

There's a list of open resources, but not sure whether there's a list of open file descriptors (including inherited ones).

Could you look into that? Mainly interested in getting that list on the parent, so we can null them.

As PHP is single threaded, closing all resources on proc_open after forking might be good enough.

Yeah that is working out really well by doing this: https://github.com/WyriHaximus/reactphp-child-process-messenger/pull/22/files#diff-8157a0d28a58887c0293ce14b4b0281fR83

[kelunik]

Not sure whether I'll get to that, don't have that much internals knowledge. Maybe @trowski?