man2/socketpair.2

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  32 .\"     @(#)socketpair.2        6.4 (Berkeley) 3/10/91
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  34 .\" Modified 1993-07-24 by Rik Faith <faith@cs.unc.edu>
  35 .\" Modified 1996-10-22 by Eric S. Raymond <esr@thyrsus.com>
  36 .\" Modified 2002-07-22 by Michael Kerrisk <mtk-manpages@gmx.net>
  37 .\" Modified 2004-06-17 by Michael Kerrisk <mtk-manpages@gmx.net>
  38 .\"
  39 .TH SOCKETPAIR 2 2004-06-17 "Linux 2.6.7" "Linux Programmer's Manual"
  40 .SH NAME
  41 socketpair \- create a pair of connected sockets
  42 .SH SYNOPSIS
  43 .B #include <sys/types.h>
  44 .br
  45 .B #include <sys/socket.h>
  46 .sp
  47 .BI "int socketpair(int " d ", int " type ", int " protocol ", int " sv [2]);
  48 .SH DESCRIPTION
  49 The
  50 .BR socketpair ()
  51 call creates an unnamed pair of connected sockets in
  52 the specified domain
  53 .IR d ,
  54 of the specified
  55 .IR type ,
  56 and using the optionally specified
  57 .IR protocol .
  58 The descriptors used in referencing the new sockets are returned in
  59 .IR sv [0]
  60 and
  61 .IR sv [1].
  62 The two sockets are indistinguishable.
  63 .SH "RETURN VALUE"
  64 On success, zero is returned.
  65 On error, \-1 is returned, and
  66 .I errno
  67 is set appropriately.
  68 .SH ERRORS
  69 .TP
  70 .B EAFNOSUPPORT
  71 The specified address family is not supported on this machine.
  72 .TP
  73 .B EFAULT
  74 The address
  75 .I sv
  76 does not specify a valid part of the process address space.
  77 .TP
  78 .B EMFILE
  79 Too many descriptors are in use by this process.
  80 .TP
  81 .B ENFILE
  82 The system limit on the total number of open files has been reached.
  83 .TP
  84 .B EOPNOTSUPP
  85 The specified protocol does not support creation of socket pairs.
  86 .TP
  87 .B EPROTONOSUPPORT
  88 The specified protocol is not supported on this machine.
  89 .SH "CONFORMING TO"
  90 4.4BSD, POSIX.1-2001.
  91 The
  92 .BR socketpair ()
  93 function call appeared in 4.2BSD. It is generally portable to/from
  94 non-BSD systems supporting clones of the BSD socket layer (including
  95 System V variants).
  96 .SH NOTES
  97 On Linux, the only supported domain for this call is
  98 .BR AF_UNIX
  99 (or synonymously,
 100 .BR AF_LOCAL ).
 101 (Most implementations have the same restriction.)
 102 .SH "SEE ALSO"
 103 .BR pipe (2),
 104 .BR read (2),
 105 .BR socket (2),
 106 .BR write (2),
 107 .BR unix (7)