socketpair - create a pair of connected sockets
Standard C library (libc, -lc)
#include <sys/socket.h>
int socketpair(int domain, int type, int protocol, int sv[2]);The socketpair() call creates an unnamed pair of
connected sockets in the specified domain, of the specified
type, and using the optionally specified protocol. For
further details of these arguments, see socket(2).
The file descriptors used in referencing the new sockets are returned
in sv[0] and sv[1]. The two sockets are
indistinguishable.
On success, zero is returned. On error, -1 is returned,
errno is set to indicate the error, and sv is left
unchanged
On Linux (and other systems), socketpair() does not
modify sv on failure. A requirement standardizing this behavior
was added in POSIX.1-2008 TC2.
The specified address family is not supported on this machine.
The address sv does not specify a valid part of the process
address space.
The per-process limit on the number of open file descriptors has been reached.
The system-wide limit on the total number of open files has been reached.
The specified protocol does not support creation of socket pairs.
The specified protocol is not supported on this machine.
On Linux, the only supported domains for this call are AF_UNIX (or synonymously, AF_LOCAL) and AF_TIPC (since Linux 4.12).
POSIX.1-2008.
POSIX.1-2001, 4.4BSD.
socketpair() first appeared in 4.2BSD. It is generally portable to/from non-BSD systems supporting clones of the BSD socket layer (including System V variants).
Since Linux 2.6.27, socketpair() supports the
SOCK_NONBLOCK and SOCK_CLOEXEC flags
in the type argument, as described in
socket(2).