Fixed issue with ssh2_poll function throwing error on valid input

[akotulu]

ssh2_poll function checks for input arguments and fails on valid stream resource with error PHP Warning: ssh2_poll(): Invalid data in subarray, no resource element, or not of type resource.

Here is a PHP function which is in use in our development environment to basically do everything from building to deploying and used in many of our internal tools. On Windows stream_select occasionally will loop indefinitely without receiving eof nor timeout. I tried to switch to ssh2_poll, but the function contains invalid resource check. I've built it from source and corrected the issue. Now the function works as indented and haven't experienced any loops.

Commented code is for using stream_select.

/**
 * Executes remote command synchronously
 *
 * @param string $command
 * @param string|null &$output
 * @param string|null &$error
 * @return bool
 */
public function exec(string $command, ?string &$output, ?string &$error): bool
{
    $stream = ssh2_exec($this->_connection, $command);
    $errorStream = ssh2_fetch_stream($stream, SSH2_STREAM_STDERR);

    stream_set_blocking($stream, true);
    stream_set_blocking($errorStream, true);

    $outputChunks = array();
    $errorChunks = array();

    $eof = function ($s) use ($command) {
        $meta = stream_get_meta_data($s);
        // Occasionally `stream_select` after command won't receive `eof` nor `to` and loops indefinitely.
        Msg::write(' [' . var_export($meta['eof'], true) . ',' . var_export($meta['timed_out'], true) . ']', false, ColorFG::Blue);
        return $meta['eof'] || $meta['timed_out'];
    };

    do {
        $read = array($stream, $errorStream);
//            $write = null;
//            $except = null;

        $polldest = array(
            array(
                'resource' => $stream,
                'events' => SSH2_POLLOUT,
            ),
            array(
                'resource' => $errorStream,
                'events' => SSH2_POLLOUT,
            ),
        );

        //if (stream_select($read, $write, $except, 5)) {
        if (ssh2_poll($polldest, 5)) {
            foreach ($read as $c) {
                if (feof($c)) {
                    continue;
                }
                $read = stream_get_line($c, 8192);

                if ($read === false) {
                    continue;
                }

                if ($c === $stream) {
                    $chunks = &$outputChunks;
                } else {
                    $chunks = &$errorChunks;
                }
                $chunks[] = $read;

                while ($line = stream_get_line($c, 8192)) {
                    $chunks[] = $line;
                }
            }
        }
    } while (!$eof($stream) | !$eof($errorStream));

    fclose($stream);
    fclose($errorStream);

    $output = implode($outputChunks);
    $error = implode($errorChunks);

    unset($outputChunks); // free up large chunks
    unset($errorChunks);

    if ((strlen($output) == 0 && strlen($error) == 0) || strlen($output) > 0) {
        return true;
    } else {
        return false;
    }
}