socketpair —
create a pair of connected sockets
#include
<sys/socket.h>
int
socketpair(
int
d,
int
type,
int
protocol,
int
sv[2]);
The
socketpair() call creates an unnamed pair
of connected sockets in the specified domain
d, of the specified
type, and using the optionally specified
protocol. The descriptors used in referencing
the new sockets are returned in
sv[0] and
sv[1]. The two sockets are indistinguishable.
Any combination of the following flags may additionally be used in the
type argument:
- SOCK_CLOEXEC
- Set close-on-exec flag on both the new descriptors.
- SOCK_NONBLOCK
- Set non-blocking I/O mode on both the new sockets.
Upon successful completion, the value 0 is returned; otherwise the
value -1 is returned and the global variable
errno is set to indicate the error.
The call succeeds unless:
-
-
- [
EAFNOSUPPORT]
- The specified address family is not supported on this machine.
-
-
- [
EPROTONOSUPPORT]
- The specified protocol is not supported on this machine.
-
-
- [
EOPNOTSUPP]
- The specified protocol does not support creation of socket pairs.
-
-
- [
EPROTOTYPE]
- The combination of the specified protocol and type is not supported.
-
-
- [
EMFILE]
- The per-process descriptor table is full.
-
-
- [
ENFILE]
- The system file table is full.
-
-
- [
ENOBUFS]
- Insufficient resources were available in the system to perform the
operation.
-
-
- [
EFAULT]
- The address sv does not specify a valid
part of the process address space.
pipe(2),
read(2),
socket(2),
write(2)
The
socketpair() function conforms to
IEEE Std 1003.1-2008
(“POSIX.1”). The
SOCK_CLOEXEC and
SOCK_NONBLOCK flags are expected to conform
to a future revision of that standard.
The
socketpair() function call appeared in
4.2BSD. Support for the
SOCK_CLOEXEC and
SOCK_NONBLOCK flags appeared in
OpenBSD 5.7.
This call is currently implemented only for the LOCAL domain. Many operating
systems only accept a
protocol of
AF_UNSPEC, so that should be used instead
of
AF_LOCAL for maximal portability.
![[OpenBSD]](/openbsd.gif){kind=small}