SOCKETPAIR(2) Linux Programmer's Manual SOCKETPAIR(2)
NAME
 socketpair - create a pair of connected sockets
SYNOPSIS
 #include <sys/types.h> /* See NOTES */
 #include <sys/socket.h>
 int socketpair(int domain, int type, int protocol, int sv[2]);
DESCRIPTION
 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.
RETURN VALUE
 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 fail-
 ure. A requirement standardizing this behavior was added in
 POSIX.1-2008 TC2.
ERRORS
 EAFNOSUPPORT
 The specified address family is not supported on this machine.
 EFAULT The address sv does not specify a valid part of the process ad-
 dress 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.
CONFORMING TO
 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).
NOTES
 On Linux, the only supported domains for this call are AF_UNIX (or syn-
 onymously, 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.
SEE ALSO
 pipe(2), read(2), socket(2), write(2), socket(7), unix(7)
COLOPHON
 This page is part of release 5.10 of the Linux man-pages project. A
 description of the project, information about reporting bugs, and the
 latest version of this page, can be found at
 https://www.kernel.org/doc/man-pages/.
Linux 2020年06月09日 SOCKETPAIR(2)