socketpair(2) on FreeBSD
The text 39b565cc5b8a, as FreeBSD 3.4-RELEASE, FreeBSD 3.3-RELEASE, FreeBSD 3.2-RELEASE, FreeBSD 3.1-RELEASE, FreeBSD 3.0-RELEASE, FreeBSD 2.2.9-RELEASE, FreeBSD 2.2.8-RELEASE, FreeBSD 2.2.7-RELEASE, FreeBSD 2.2.6-RELEASE, FreeBSD 2.2.5-RELEASE, FreeBSD 2.2.2-RELEASE shipped it.
create a pair of connected sockets