SOCKETPAIR(3XNET) X/Open Networking Services Library Functions

NAME

socketpair - create a pair of connected sockets

SYNOPSIS

cc [ flag ... ] file ... -lxnet [ library ... ]
#include <sys/socket.h>

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

DESCRIPTION

The socketpair() function creates 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 are identical. The
file descriptors used in referencing the created sockets are returned in
socket_vector0 and socket_vector1.


The type argument specifies the socket type, which determines the
semantics of communications over the socket. The socket types supported
by the system are implementation-dependent. Possible socket types
include:

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 path 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 must specify a protocol that is
supported by the address family. The protocols supported by the system
are implementation-dependent.


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

PARAMETERS

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.

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.

RETURN VALUES

Upon successful completion, this function returns 0. Otherwise, -1 is
returned and errno is set to indicate the error.

ERRORS

The socketpair() function will 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.


ENOSR
There were insufficient STREAMS resources available for the
operation to complete.

ATTRIBUTES

See attributes(7) for descriptions of the following attributes:


+--------------------+-----------------+
| ATTRIBUTE TYPE | ATTRIBUTE VALUE |
+--------------------+-----------------+
|Interface Stability | Standard |
+--------------------+-----------------+
|MT-Level | MT-Safe |
+--------------------+-----------------+

SEE ALSO

socket(3XNET), attributes(7), standards(7)

June 10, 2002 SOCKETPAIR(3XNET)