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
185 lines
5.1 KiB
Groff
185 lines
5.1 KiB
Groff
.\" $NetBSD: accept.2,v 1.25 2006/11/17 23:59:33 rillig Exp $
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.\"
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.\" Copyright (c) 1983, 1990, 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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.\" @(#)accept.2 8.2 (Berkeley) 12/11/93
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.\"
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.Dd November 18, 2006
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.Dt ACCEPT 2
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.Os
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.Sh NAME
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.Nm accept
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.Nd accept a connection on 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 int
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.Fn accept "int s" "struct sockaddr * restrict addr" "socklen_t * restrict addrlen"
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.Sh DESCRIPTION
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The argument
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.Fa s
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is a socket that has been created with
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.Xr socket 2 ,
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bound to an address with
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.Xr bind 2 ,
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and is listening for connections after a
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.Xr listen 2 .
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The
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.Fn accept
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argument
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extracts the first connection request on the queue of pending
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connections, creates a new socket with the same properties of
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.Fa s
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and allocates a new file descriptor
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for the socket.
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If no pending connections are
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present on the queue, and the socket is not marked
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as non-blocking,
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.Fn accept
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blocks the caller until a connection is present.
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If the socket is marked non-blocking and no pending
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connections are present on the queue,
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.Fn accept
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returns an error as described below.
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The accepted socket
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may not be used
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to accept more connections.
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The original socket
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.Fa s
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remains open.
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.Pp
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The argument
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.Fa addr
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is a result parameter that is filled in with
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the address of the connecting entity,
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as known to the communications layer.
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The exact format of the
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.Fa addr
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parameter is determined by the domain in which the communication
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is occurring.
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The
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.Fa addrlen
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is a value-result parameter; it should initially contain the
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amount of space pointed to by
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.Fa addr ;
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on return it will contain the actual length (in bytes) of the
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address returned.
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This call
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is used with connection-based socket types, currently with
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.Dv SOCK_STREAM .
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.Pp
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It is possible to
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.Xr select 2
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or
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.Xr poll 2
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a socket for the purposes of doing an
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.Fn accept
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by selecting or polling it for read.
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.Pp
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For certain protocols which require an explicit confirmation,
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such as
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.Tn ISO
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or
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.Tn DATAKIT ,
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.Fn accept
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can be thought of
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as merely dequeuing the next connection
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request and not implying confirmation.
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Confirmation can be implied by a normal read or write on the new
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file descriptor, and rejection can be implied by closing the
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new socket.
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.Pp
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One can obtain user connection request data without confirming
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the connection by issuing a
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.Xr recvmsg 2
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call with an
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.Fa msg_iovlen
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of 0 and a non-zero
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.Fa msg_controllen ,
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or by issuing a
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.Xr getsockopt 2
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request.
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Similarly, one can provide user connection rejection information
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by issuing a
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.Xr sendmsg 2
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call with providing only the control information,
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or by calling
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.Xr setsockopt 2 .
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.Sh RETURN VALUES
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The call returns \-1 on error.
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If it succeeds, it returns a non-negative
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integer that is a descriptor for the accepted socket.
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.Sh ERRORS
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The
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.Fn accept
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will fail if:
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.Bl -tag -width Er
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.It Bq Er EAGAIN
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The socket is marked non-blocking and no connections
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are present to be accepted.
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.It Bq Er EBADF
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The descriptor is invalid.
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.It Bq Er ECONNABORTED
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A connection has been aborted.
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.It Bq Er EFAULT
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The
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.Fa addr
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parameter is not in a writable part of the
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user address space.
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.It Bq Er EINTR
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The
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.Fn accept
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call has been interrupted by a signal.
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.It Bq Er EINVAL
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The socket has not been set up to accept connections (using
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.Xr bind 2
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and
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.Xr listen 2 ) .
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.It Bq Er EMFILE
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The per-process descriptor table is full.
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.It Bq Er ENFILE
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The system file table is full.
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.It Bq Er ENOTSOCK
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The descriptor references a file, not a socket.
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.It Bq Er EOPNOTSUPP
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The referenced socket is not of type
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.Dv SOCK_STREAM .
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.El
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.Sh SEE ALSO
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.Xr bind 2 ,
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.Xr connect 2 ,
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.Xr listen 2 ,
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.Xr poll 2 ,
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.Xr select 2 ,
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.Xr socket 2
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.Sh HISTORY
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The
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.Fn accept
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function appeared in
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.Bx 4.2 .
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