create a pair of connected
domain, int type,
call creates an unnamed pair of connected sockets. The descriptors used in
referencing the new sockets are returned in sv and
sv. The two sockets are indistinguishable.
The only supported domain is
AF_UNIX. Possible values for the
type and protocol arguments are
explained in the
socket(2) manual page. The only useful value for
protocol is 0, which will let the system select an
appropriate protocol for the requested socket
Any combination of the following flags may additionally be used in the type argument:
- Set close-on-exec flag on both the new descriptors.
- 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:
- The specified address family is not supported on this machine.
- The specified protocol is not supported on this machine.
- The specified protocol does not support creation of socket pairs.
- The combination of the specified protocol and type is not supported.
- The per-process descriptor table is full.
- The system file table is full.
- Insufficient resources were available in the system to perform the operation.
- The address sv does not specify a valid part of the process address space.
pipe(2), read(2), socket(2), write(2)
socketpair() function conforms to
IEEE Std 1003.1-2008 (“POSIX.1”). The
SOCK_NONBLOCK flags are expected to conform to a
future revision of that standard.
socketpair() function call appeared in
4.2BSD. Support for the
SOCK_NONBLOCK flags appeared in