The resource returned by stream_socket_accept may have incorrect metadata

[ichaoX]

Description

The following code:

<?php

function setNonBlocking($stream)
{
    var_dump($block = stream_get_meta_data($stream)['blocked']);
    if ($block) {
        stream_set_blocking($stream, false);
        var_dump(stream_get_meta_data($stream)['blocked']);
    }
}

$server = stream_socket_server("tcp://127.0.0.1:4321");
setNonBlocking($server);

$client = stream_socket_client("tcp://127.0.0.1:4321");

$res = stream_socket_accept($server);
setNonBlocking($res);
// Removing the following line will cause blocking
// stream_set_blocking($res,false);

fwrite($client,str_repeat('0',5));

var_dump(fread($res,4));
var_dump(fread($res,4));

Resulted in this output:

bool(true)
bool(false)
bool(false)
string(4) "0000"

But I expected this output instead:

bool(true)
bool(false)
bool(true)
bool(false)
string(4) "0000"
string(1) "0"

PHP Version

PHP 8.1.2, PHP 7.4.14

Operating System

Debian

[bwoebi]

The problem lies within php_tcp_sockop_accept / php_openssl_tcp_sockop_accept which unconditionally inherits the properties from the server socket. I.e. if the server socket is non-blocking, the client socket will be marked non-blocking as well, without actually being non-blocking.

(This behaviour is different between Linux and Windows/BSD I believe? - according to my unscientific research Windows/BSD are actually inheriting the non-blockingness.)