2fe8fb192f
There is important information about booting non-ack images in docs/UPDATING. ack/aout-format images can't be built any more, and booting clang/ELF-format ones is a little different. Updating to the new boot monitor is recommended. Changes in this commit: . drop boot monitor -> allowing dropping ack support . facility to copy ELF boot files to /boot so that old boot monitor can still boot fairly easily, see UPDATING . no more ack-format libraries -> single-case libraries . some cleanup of OBJECT_FMT, COMPILER_TYPE, etc cases . drop several ack toolchain commands, but not all support commands (e.g. aal is gone but acksize is not yet). . a few libc files moved to netbsd libc dir . new /bin/date as minix date used code in libc/ . test compile fix . harmonize includes . /usr/lib is no longer special: without ack, /usr/lib plays no kind of special bootstrapping role any more and bootstrapping is done exclusively through packages, so releases depend even less on the state of the machine making them now. . rename nbsd_lib* to lib* . reduce mtree
221 lines
6.3 KiB
Groff
221 lines
6.3 KiB
Groff
.\" $NetBSD: send.2,v 1.27 2008/05/09 15:52:50 christos Exp $
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.\"
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.\" Copyright (c) 1983, 1991, 1993
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.\" The Regents of the University of California. All rights reserved.
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.\"
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.\" Redistribution and use in source and binary forms, with or without
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.\" modification, are permitted provided that the following conditions
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.\" are met:
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.\" 1. Redistributions of source code must retain the above copyright
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.\" notice, this list of conditions and the following disclaimer.
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.\" 2. Redistributions in binary form must reproduce the above copyright
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.\" notice, this list of conditions and the following disclaimer in the
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.\" documentation and/or other materials provided with the distribution.
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.\" 3. Neither the name of the University nor the names of its contributors
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.\" may be used to endorse or promote products derived from this software
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.\" without specific prior written permission.
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.\"
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.\" THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
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.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
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.\" ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
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.\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
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.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
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.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
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.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
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.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
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.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
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.\" SUCH DAMAGE.
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.\"
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.\" @(#)send.2 8.2 (Berkeley) 2/21/94
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.\"
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.Dd May 9, 2008
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.Dt SEND 2
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.Os
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.Sh NAME
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.Nm send ,
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.Nm sendto ,
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.Nm sendmsg
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.Nd send a message from a socket
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.Sh LIBRARY
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.Lb libc
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.Sh SYNOPSIS
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.In sys/socket.h
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.Ft ssize_t
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.Fn send "int s" "const void *msg" "size_t len" "int flags"
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.Ft ssize_t
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.Fn sendto "int s" "const void *msg" "size_t len" "int flags" "const struct sockaddr *to" "socklen_t tolen"
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.Ft ssize_t
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.Fn sendmsg "int s" "const struct msghdr *msg" "int flags"
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.Sh DESCRIPTION
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.Fn send ,
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.Fn sendto ,
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and
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.Fn sendmsg
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are used to transmit a message to another socket.
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.Fn send
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may be used only when the socket is in a
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.Em connected
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state, while
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.Fn sendto
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and
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.Fn sendmsg
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may be used at any time.
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.Pp
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The address of the target is given by
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.Fa to
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with
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.Fa tolen
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specifying its size.
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The length of the message is given by
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.Fa len .
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If the message is too long to pass atomically through the
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underlying protocol, the error
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.Er EMSGSIZE
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is returned, and
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the message is not transmitted.
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.Pp
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No indication of failure to deliver is implicit in a
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.Fn send .
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Locally detected errors are indicated by a return value of \-1.
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.Pp
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If no messages space is available at the socket to hold
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the message to be transmitted, then
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.Fn send
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normally blocks, unless the socket has been placed in
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non-blocking I/O mode.
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The
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.Xr select 2
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or
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.Xr poll 2
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call may be used to determine when it is possible to
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send more data.
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.Pp
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The
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.Fa flags
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parameter may include one or more of the following:
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.Bd -literal
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#define MSG_OOB 0x0001 /* process out-of-band data */
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#define MSG_PEEK 0x0002 /* peek at incoming message */
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#define MSG_DONTROUTE 0x0004 /* bypass routing, use direct interface */
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#define MSG_EOR 0x0008 /* data completes record */
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#define MSG_NOSIGNAL 0x0400 /* do not generate SIGPIPE on EOF */
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.Ed
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.Pp
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The flag
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.Dv MSG_OOB
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is used to send
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.Dq out-of-band
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data on sockets that support this notion (e.g.
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.Dv SOCK_STREAM ) ;
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the underlying protocol must also support
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.Dq out-of-band
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data.
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.Dv MSG_EOR
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is used to indicate a record mark for protocols which support the
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concept.
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.\" .Dv MSG_EOF
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.\" requests that the sender side of a socket be shut down, and that an
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.\" appropriate indication be sent at the end of the specified data;
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.\" this flag is only implemented for
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.\" .Dv SOCK_STREAM
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.\" sockets in the
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.\" .Dv PF_INET
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.\" protocol family, and is used to implement Transaction
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.\" .Tn TCP
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.\" (see
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.\" .Xr ttcp 4 ) .
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.Dv MSG_DONTROUTE
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is usually used only by diagnostic or routing programs.
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.Pp
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See
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.Xr recv 2
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for a description of the
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.Fa msghdr
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structure.
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.Dv MSG_NOSIGNAL
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is used to prevent
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.Dv SIGPIPE
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generation when writing a socket that
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may be closed.
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.Sh RETURN VALUES
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The call returns the number of characters sent, or \-1
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if an error occurred.
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.Sh ERRORS
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.Fn send ,
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.Fn sendto ,
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and
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.Fn sendmsg
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fail if:
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.Bl -tag -width Er
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.It Bq Er EBADF
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An invalid descriptor was specified.
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.It Bq Er ENOTSOCK
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The argument
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.Fa s
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is not a socket.
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.It Bq Er EFAULT
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An invalid user space address was specified for a parameter.
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.It Bq Er EMSGSIZE
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The socket requires that message be sent atomically,
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and the size of the message to be sent made this impossible.
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.It Bq Er EPIPE
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In a connected socket the connection has been broken.
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.It Bq Er EDSTADDRREQ
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In a non-connected socket a destination address has not been specified.
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.It Bq Er EAGAIN|EWOULDBLOCK
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The socket is marked non-blocking and the requested operation
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would block.
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.It Bq Er ENOBUFS
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The system was unable to allocate an internal buffer.
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The operation may succeed when buffers become available.
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.It Bq Er ENOBUFS
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The output queue for a network interface was full.
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This generally indicates that the interface has stopped sending,
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but may be caused by transient congestion.
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.It Bq Er EACCES
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The SO_BROADCAST option is not set on the socket, and a broadcast address
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was given as the destination.
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.It Bq Er EHOSTUNREACH
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The destination for the message is unreachable.
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.It Bq Er EHOSTDOWN
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The destination is a host on the local subnet and does not respond to
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.Xr arp 4 .
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.It Bq Er EINVAL
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The total length of the I/O is more than can be expressed by the ssize_t
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return value.
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.It Bq Er EAFNOSUPPORT
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Addresses in the specified address family cannot be used with this socket.
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.El
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.Pp
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.Fn sendto
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will also fail if:
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.Bl -tag -width Er
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.It Bq Er EISCONN
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A destination address was specified and the socket is already connected.
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.El
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.Pp
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.Fn sendmsg
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will also fail if:
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.Bl -tag -width Er
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.It Bq Er EMSGSIZE
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The
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.Fa msg_iovlen
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member of the
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.Fa msg
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structure is less than or equal to 0
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or is greater than
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.Dv {IOV_MAX} .
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.El
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.Sh SEE ALSO
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.Xr fcntl 2 ,
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.Xr getsockopt 2 ,
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.Xr recv 2 ,
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.Xr select 2 ,
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.Xr socket 2 ,
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.Xr write 2
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.Sh HISTORY
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The
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.Fn send
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function call appeared in
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.Bx 4.2 .
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