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SOCKETPAIR(2) Linux Programmer's Manual SOCKETPAIR(2)

NAME

     socketpair - create a pair of connected sockets

SYNOPSIS

     #include <sys/types.h>          /* See NOTES */
     #include <sys/socket.h>

     int socketpair(int domain, int type, int protocol, int sv[2]);

DESCRIPTION

     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.

RETURN VALUE

     On  success,  zero is returned.  On error, -1 is returned, and errno is
     set appropriately.

     On Linux (and other systems), socketpair() does not modify sv on  fail-
     ure.    A   requirement   standardizing  this  behavior  was  added  in
     POSIX.1-2016.

ERRORS

     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 The per-process limit on the number of open file descriptors has
            been reached.

     ENFILE The system-wide limit on the total number of open files has been
            reached.

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

     EPROTONOSUPPORT
            The specified protocol is not supported on this machine.

CONFORMING TO

     POSIX.1-2001, POSIX.1-2008, 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).

NOTES

     On Linux, the only supported domain for this call is AF_UNIX  (or  syn-
     onymously,  AF_LOCAL).   (Most  implementations  have the same restric-
     tion.)

     Since  Linux  2.6.27,  socketpair()  supports  the  SOCK_NONBLOCK   and
     SOCK_CLOEXEC flags in the type argument, as described in socket(2).

     POSIX.1  does  not  require  the  inclusion  of <sys/types.h>, and this
     header file is not required on Linux.  However, some  historical  (BSD)
     implementations  required  this  header file, and portable applications
     are probably wise to include it.

SEE ALSO

     pipe(2), read(2), socket(2), write(2), socket(7), unix(7)

COLOPHON

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     description  of  the project, information about reporting bugs, and the
     latest    version    of    this    page,    can     be     found     at
     https://www.kernel.org/doc/man-pages/.

Linux 2017-09-15 SOCKETPAIR(2)