Updated: 2022/Sep/29

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SOCKETPAIR(2)                 System Calls Manual                SOCKETPAIR(2)

NAME
     socketpair - create a pair of connected sockets

LIBRARY
     Standard C Library (libc, -lc)

SYNOPSIS
     #include <sys/socket.h>

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

DESCRIPTION
     The socketpair() call creates an unnamed pair of connected sockets in the
     specified domain d, 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.

     Possible values for the type argument are SOCK_STREAM, SOCK_DGRAM, and
     SOCK_SEQPACKET; the only supported value for the protocol is 0, which
     will let the system select an appropriate protocol for the requested
     socket type.

     Any combination of the following flags may additionally be used in the
     type argument:

           SOCK_CLOEXEC  Set close-on-exec flag on both the new descriptors.
           SOCK_NONBLOCK
                         Set non-blocking I/O mode on both the new sockets.

RETURN VALUES
     Upon successful completion, the value 0 is returned; otherwise the
     value -1 is returned and the global variable errno is set to indicate the
     error.

ERRORS
     The call succeeds unless:

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

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

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

     [ENFILE]           The system file table is full.

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

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

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

HISTORY
     The socketpair() function call appeared in 4.2BSD.

     Support for the SOCK_CLOEXEC and SOCK_NONBLOCK flags appeared in
     NetBSD 6.0.

BUGS
     This call is currently implemented only for the PF_LOCAL domain.

NetBSD 10.99                   November 29, 2022                  NetBSD 10.99