socketpair

SOCKETPAIR(3POSIX)          POSIX Programmer's Manual         SOCKETPAIR(3POSIX)



PROLOG
       This manual page is part of the POSIX Programmer's Manual.  The Linux
       implementation of this interface may differ (consult the corresponding
       Linux manual page for details of Linux behavior), or the interface may
       not be implemented on Linux.


NAME
       socketpair — create a pair of connected sockets

SYNOPSIS
       #include <sys/socket.h>

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

DESCRIPTION
       The socketpair() function shall create an unbound pair of connected
       sockets in a specified domain, of a specified type, under the protocol
       optionally specified by the protocol argument. The two sockets shall be
       identical. The file descriptors used in referencing the created sockets
       shall be returned in socket_vector[0] and socket_vector[1].

       The socketpair() function takes the following arguments:

       domain      Specifies the communications domain in which the sockets are
                   to be created.

       type        Specifies the type of sockets to be created.

       protocol    Specifies a particular protocol to be used with the sockets.
                   Specifying a protocol of 0 causes socketpair() to use an
                   unspecified default protocol appropriate for the requested
                   socket type.

       socket_vector
                   Specifies a 2-integer array to hold the file descriptors of
                   the created socket pair.

       The type argument specifies the socket type, which determines the
       semantics of communications over the socket. The following socket types
       are defined; implementations may specify additional socket types:

       SOCK_STREAM   Provides sequenced, reliable, bidirectional, connection-
                     mode byte streams, and may provide a transmission mechanism
                     for out-of-band data.

       SOCK_DGRAM    Provides datagrams, which are connectionless-mode,
                     unreliable messages of fixed maximum length.

       SOCK_SEQPACKET
                     Provides sequenced, reliable, bidirectional, connection-
                     mode transmission paths for records. A record can be sent
                     using one or more output operations and received using one
                     or more input operations, but a single operation never
                     transfers part of more than one record. Record boundaries
                     are visible to the receiver via the MSG_EOR flag.

       If the protocol argument is non-zero, it shall specify a protocol that is
       supported by the address family. If the protocol argument is zero, the
       default protocol for this address family and type shall be used. The
       protocols supported by the system are implementation-defined.

       The process may need to have appropriate privileges to use the
       socketpair() function or to create some sockets.

RETURN VALUE
       Upon successful completion, this function shall return 0; otherwise, −1
       shall be returned and errno set to indicate the error.

ERRORS
       The socketpair() function shall fail if:

       EAFNOSUPPORT
              The implementation does not support the specified address family.

       EMFILE All, or all but one, of the file descriptors available to the
              process are currently open.

       ENFILE No more file descriptors are available for the system.

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

       EPROTONOSUPPORT
              The protocol is not supported by the address family, or the
              protocol is not supported by the implementation.

       EPROTOTYPE
              The socket type is not supported by the protocol.

       The socketpair() function may fail if:

       EACCES The process does not have appropriate privileges.

       ENOBUFS
              Insufficient resources were available in the system to perform the
              operation.

       ENOMEM Insufficient memory was available to fulfill the request.

       The following sections are informative.

EXAMPLES
       None.

APPLICATION USAGE
       The documentation for specific address families specifies which protocols
       each address family supports. The documentation for specific protocols
       specifies which socket types each protocol supports.

       The socketpair() function is used primarily with UNIX domain sockets and
       need not be supported for other domains.

RATIONALE
       None.

FUTURE DIRECTIONS
       None.

SEE ALSO
       socket()

       The Base Definitions volume of POSIX.1‐2008, <sys_socket.h>

COPYRIGHT
       Portions of this text are reprinted and reproduced in electronic form
       from IEEE Std 1003.1, 2013 Edition, Standard for Information Technology
       -- Portable Operating System Interface (POSIX), The Open Group Base
       Specifications Issue 7, Copyright (C) 2013 by the Institute of Electrical
       and Electronics Engineers, Inc and The Open Group.  (This is POSIX.1-2008
       with the 2013 Technical Corrigendum 1 applied.) In the event of any
       discrepancy between this version and the original IEEE and The Open Group
       Standard, the original IEEE and The Open Group Standard is the referee
       document. The original Standard can be obtained online at
       http://www.unix.org/online.html .

       Any typographical or formatting errors that appear in this page are most
       likely to have been introduced during the conversion of the source files
       to man page format. To report such errors, see
       https://www.kernel.org/doc/man-pages/reporting_bugs.html .



IEEE/The Open Group                   2013                    SOCKETPAIR(3POSIX)