trusty (3) socketpair.3posix.gz

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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 No more file descriptors are available for this process.

       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 IEEE Std 1003.1-2001, <sys/socket.h>


       Portions of this text are reprinted and reproduced in electronic form from IEEE Std 1003.1, 2003 Edition,
       Standard for Information Technology -- Portable Operating System Interface (POSIX), The Open  Group  Base
       Specifications Issue 6, Copyright (C) 2001-2003 by the Institute of Electrical and Electronics Engineers,
       Inc and The Open Group. 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.opengroup.org/unix/online.html .