SOCKETPAIR(2)             FreeBSD System Calls Manual            SOCKETPAIR(2)

NAME

     socketpair - create a pair of connected sockets

LIBRARY

     Standard C Library (libc, -lc)

SYNOPSIS

     #include <sys/types.h>
     #include <sys/socket.h>

     int
     socketpair(int domain, int type, int protocol, int *sv);

DESCRIPTION

     The socketpair() system call creates an unnamed pair of connected sockets
     in the specified communications domain, of the specified type, and using
     the optionally specified protocol.  The descriptors used in referencing
     the new sockets are returned in sv[0] and sv[1].  The two sockets are
     indistinguishable.

     The SOCK_CLOEXEC, SOCK_CLOFORK and SOCK_NONBLOCK flags in the type
     argument apply to both descriptors.

RETURN VALUES

     The socketpair() function returns the value 0 if successful; otherwise
     the value -1 is returned and the global variable errno is set to indicate
     the error.

ERRORS

     The call succeeds unless:

     [EMFILE]           Too many descriptors are in use by this process.

     [EAFNOSUPPORT]     The specified address family is not supported on this
                        machine.

     [EPROTONOSUPPORT]  The specified protocol is not supported on this
                        machine.

     [EOPNOTSUPP]       The specified protocol does not support creation of
                        socket pairs.

     [EFAULT]           The address sv does not specify a valid part of the
                        process address space.

SEE ALSO

     pipe(2), read(2), socket(2), write(2)

STANDARDS

     The socketpair() system call conforms to IEEE Std 1003.1-2001 ("POSIX.1")
     and IEEE Std 1003.1-2008 ("POSIX.1").

HISTORY

     The socketpair() system call appeared in 4.2BSD.

BUGS

     This call is currently implemented only for the Unix domain.

FreeBSD 15.1-STABLE-HBSD         May 17, 2025                    SOCKETPAIR(2)