kqueue on OSX broke support for read-only file descriptors

[alexander.afanasyev@…]

Prior 1.56, we were successfully using boost::asio::posix::stream_descriptor with libpcap (file descriptor retrieved via pcap_get_selectable_fd).

My understanding, that change https_github.com_boostorg_asio_commit_660e9fe30204e0ada0d1fd40c48015810d2647dc (replace _ with /) required all file-descriptors to be both readable and writeable (e.g., register_descriptor always registers EVFILT_READ and EVFILT_WRITE events).

In the case of libpcap, the file descriptor only works in one direction (read) and attempt to register EVFILT_WRITE event results in assign: Invalid argument error.