socketpair - create a pair of connected sockets
#include <sys/types.h> /* See NOTES */
#include <sys/socket.h>
int socketpair(int domain, int type, int
protocol, int sv[2]);
The
socketpair() call creates an unnamed pair of connected sockets in the
specified
domain, of the specified
type, and using the
optionally specified
protocol. For further details of these arguments,
see
socket(2).
The file descriptors used in referencing the new sockets are returned in
sv[0] and
sv[1]. The two sockets are indistinguishable.
On success, zero is returned. On error, -1 is returned,
errno is set
appropriately, and
sv is left unchanged
On Linux (and other systems),
socketpair() does not modify
sv on
failure. A requirement standardizing this behavior was added in POSIX.1-2016.
- EAFNOSUPPORT
- The specified address family is not supported on this machine.
- EFAULT
- The address sv does not specify a valid part of the process address
space.
- EMFILE
- The per-process limit on the number of open file descriptors has been
reached.
- ENFILE
- The system-wide limit on the total number of open files has been
reached.
- EOPNOTSUPP
- The specified protocol does not support creation of socket pairs.
- EPROTONOSUPPORT
- The specified protocol is not supported on this machine.
POSIX.1-2001, POSIX.1-2008, 4.4BSD.
socketpair() first 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 domains for this call are
AF_UNIX (or
synonymously,
AF_LOCAL) and
AF_TIPC (since Linux 4.12).
Since Linux 2.6.27,
socketpair() supports the
SOCK_NONBLOCK and
SOCK_CLOEXEC flags in the
type argument, as described in
socket(2).
POSIX.1 does not require the inclusion of
<sys/types.h>, 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.
pipe(2),
read(2),
socket(2),
write(2),
socket(7),
unix(7)