`basic_stream_socket::read_some` on `non_blocked` socket returns `ec=would_block`

[Dmytro Ovdiienko <dmitriyovdienko@…>]

In the boost\asio\detail\impl\socket_ops.ipp file there is sync_recv function which should block until some data is received.

Inside this function there is following if block

    if ((state & user_set_non_blocking)
        || (ec != boost::asio::error::would_block
          && ec != boost::asio::error::try_again))
      return 0;

IMHO condition is wrong here. It should return 0 for all cases except socket is in non_blocking mode and ec is one of [would_block, try_again]

In fact if socket is in 'non-blocked' mode and ec = would_block, it also returns 0.

If assumption is correct, code should look like

    if (0 == (state & user_set_non_blocking)
        || (ec != boost::asio::error::would_block
          && ec != boost::asio::error::try_again))
      return 0;

[Dmytro Ovdiienko <dmitriyovdienko@…>]

Probably, I read documentation wrong. It should block in case of blocked socket.