MFC 197775,197777-197779,197781,197794,243152,243313,255478:
First cut at implementing SOCK_SEQPACKET support for UNIX (local) domain
sockets. This allows for reliable bi-directional datagram communication
over UNIX domain sockets, in contrast to SOCK_DGRAM (M:N, unreliable) or
SOCK_STERAM (bi-directional bytestream). Largely, this reuses existing
UNIX domain socket code. This allows applications requiring record-
oriented semantics to do so reliably via local IPC.
git-svn-id: svn://svn.freebsd.org/base/stable/8@260606
ccf9f872-aa2e-dd11-9fc8-
001c23d0bc1f