pubread(), pubwrite(), pubseek(), pubaccept(), pubconnect() and pubclose() are the equivalent to their non-"pub" versions, except that they are virtual. x::fd implements read(), write(), seek() and connect() as inline functions that are suitable for compile-time optimizations, and implements the pub methods by invoking the non-pub functions. accept() is not inlined, but it's inherited from x::fdbase.

pubread_pending() returns the number of unread bytes that are waiting to be read. If the next call to pubread() specifies not more than the returned number of bytes, pubread() is guaranteed to return immediately, without blocking.

The implementation in x::fd always returns 0. The TLS session object passes through this method to the underlying library. An encrypted bytestream gets transferred in large blocks, which are then doled out, piecemeal, by pubread(), so at a given time there may be additional data that's available to be read.

getistream(), getostream() and getiostream() return a reference-counted stream object.

get_fd() returns the underlying open file descriptor.