SOCKETPAIR(P) SOCKETPAIR(P)
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 argu-
ment. 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 communica-
tions 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 sup-
ported 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 sup-
ported for other domains.
RATIONALE
None.
FUTURE DIRECTIONS
None.
SEE ALSO
socket() , the Base Definitions volume of IEEE Std 1003.1-2001, <sys/socket.h>
COPYRIGHT
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 orig-
inal Standard can be obtained online at http://www.opengroup.org/unix/online.html .
POSIX 2003 SOCKETPAIR(P)
|