how to determine errno on user space?

Hi, I'm writing some socket client (fluentd client) with PHP and I have a question. I want to retry fwrite or some socket function when I met recoverable errno (e.g, EAGAIN). but PHP does not have any function to determine errno as far as I known. what is the correct way to handle errno? I'd like to write robust client with PHP but I don't have good idea to determine errno. I'm thinking and thinking about this issue long time. I inspired ruby's errno module ( http://www.ruby-doc.org/docs/ProgrammingRuby/html/ref_m_errno.html) and I just wrote errno extension to check my idea. I think importing errno module is not a bad idea. https://github.com/chobie/php-errno/blob/master/php_errno.c (currently, this lacks const_missing feature so this does not work on some platform. ) Could you help me out if you guys have good solution about handling socket error? Thanks, Shuhei