int socketpair(int domain, int type, int protocol, int sv);
call creates an unnamed pair of connected sockets in the specified
of the specified
and using the optionally specified
For further details of these arguments, see
The descriptors used in referencing the new sockets are returned in
The two sockets are indistinguishable.
On success, zero is returned.
On error, -1 is returned, and
is set appropriately.
The specified address family is not supported on this machine.
does not specify a valid part of the process address space.
Too many descriptors are in use by this process.
The system limit on the total number of open files has been reached.
The specified protocol does not support creation of socket pairs.
The specified protocol is not supported on this machine.
function call appeared in 4.2BSD.
It is generally portable to/from
non-BSD systems supporting clones of the BSD socket layer (including
System V variants).
On Linux, the only supported domain for this call is
(Most implementations have the same restriction.)
Since Linux 2.6.27,
flags described in
POSIX.1-2001 does not require the inclusion of
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.