io_socketpair - Man Page
create a pair of sockets
Syntax
#include <io.h>
int io_socketpair(int64 pfd[2]);
Description
io_socketpair creates a new UNIX socket pair and writes both descriptors to d. The socket pair works much like a pipe, but it is bidirectional (i.e. both descriptors are for reading and writing).
io_socketpair returns 1 to indicate success. If something goes wrong, io_socketpair returns 0, setting errno to indicate the error; in this case it frees any memory that it allocated for the new socketpair, and it leaves d alone.