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.\" All rights reserved.
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.\" modification, are permitted provided that the following conditions
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.\" 3. All advertising materials mentioning features or use of this software
.\"    must display the following acknowledgement:
.\"	This product includes software developed by the University of
.\"	California, Berkeley and its contributors.
.\" 4. Neither the name of the University nor the names of its contributors
.\"    may be used to endorse or promote products derived from this software
.\"    without specific prior written permission.
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.\" THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
.\" ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
.\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
.\" SUCH DAMAGE.
.\"
.\" Modified 1993-07-24 by Rik Faith <faith@cs.unc.edu>
.\" Modified 1996-10-21 by Eric S. Raymond <esr@thyrsus.com>
.\" Modified 1998-2000 by Andi Kleen to match Linux 2.2 reality
.\" Modified 2002-04-23 by Roger Luethi <rl@hellgate.ch>
.\" Modified 2004-06-17 by Michael Kerrisk <mtk.manpages@gmail.com>
.\" 2008-12-04, mtk, Add documentation of accept4()
.\"
.\" Japanese Version Copyright (c) 1998-2000 Shinya HANATAKA,
.\"   Takeshi Hakamada and NAKANO Takeo
.\"         all rights reserved.
.\" Translated 1998-04-06, Shinya HANATAKA <shinya@abyss.rim.or.jp>
.\"                        Takeshi Hakamada <hakamada@nsg.sgi.com>
.\" Updated & Modified 2000-10-12, NAKANO Takeo <nakano@apm.seikei.ac.jp
.\" Updated & Modified 2002-09-24, Akihiro MOTOKI <amotoki@dd.iij4u.or.jp>
.\" Updated & Modified 2005-02-23, Akihiro MOTOKI
.\" Updated & Modified 2006-04-14, Akihiro MOTOKI, LDP v2.29
.\" Updated & Modified 2008-12-24, Akihiro MOTOKI, LDP v3.15
.\" Updated 2008-04-13, Akihiro MOTOKI, LDP v3.20
.\"
.\"WORD:	pending			α
.\"WORD:	queue			塼
.\"WORD:	file descriptor		ե롦ǥץ
.\"WORD:	non-blocking		
.\"WORD:	async			Ʊ
.\"WORD:	communication layer	̿
.\"WORD:	value-result argument	ξѤΰ
.\"WORD:	confirmation		³ǧ
.\"WORD:	dequeue			塼Ф
.\"WORD:	rejection		³
.\"
.TH ACCEPT 2 2009-02-23 "Linux" "Linux Programmer's Manual"
.SH ̾
accept \- åȤؤ³
.SH 
.nf
.BR "#include <sys/types.h>" "          /* ա׻ */"
.B #include <sys/socket.h>

.BI "int accept(int " sockfd ", struct sockaddr *" addr ", socklen_t *" addrlen );

.B #define _GNU_SOURCE
.B #include <sys/socket.h>

.BI "int accept4(int " sockfd ", struct sockaddr *" addr ,
.BI "            socklen_t *" addrlen ", int " flags );
.fi
.SH 
.BR accept ()
ƥॳϡ³ظΥåȷ
.RB ( SOCK_STREAM ", " SOCK_SEQPACKET )
Ѥ롣
δؿϡ³Ԥå
.I socket
Ƥα֤³׵᤬äƤ륭塼
Ƭ³׵Ф³ѤߥåȤ򿷵
ΥåȤ򻲾Ȥ뿷ե롦ǥץ֤
줿åȤϡ³Ԥ (listen) ֤ǤϤʤ
ȤȤΥå
.I sockfd
ϤθƤӽФˤäƱƶʤ
.PP

.I sockfd
ϡ
.BR socket (2)
ˤä졢
.BR bind (2)
ˤäƥ륢ɥ쥹˥Хɤ졢
.BR listen (2)
Ф³ԤäƤ륽åȤǤ롣

.I addr

.I sockaddr
¤ΤؤΥݥ󥿤Ǥ롣
ι¤Τˤ³ΥåȤΥɥ쥹äƤ롣
.I addr
֤륢ɥ쥹ΤʥեޥåȤϡ
åȤΥɥ쥹̤ˤäѤ
.RB ( socket (2)
Ӥ줾Υץȥ man ڡ򻲾)
.I addr
 NULL ξ硢
.I addr
ˤϲʤξ硢
.I addrlen
ϻѤ줺ΰ NULL ˤƤ٤Ǥ롣

.I addrlen
ξѤΰǤ롣ƤӽФˤϡƤӽФ
.I addr
ؤ¤ΤΥ (Хñ) ǽƤʤФʤʤ
֤äƤˤϡ³Υɥ쥹μºݤ礭Ǽ롣

Ϥ줿Хåե᤮ˤϡ֤륢ɥ쥹
ڤͤ롣ξˤϡ
.I addrlen
ǤϡƤӽФϤ줿ͤ礭֤ͤ롣
.PP
塼αȤʤäƤ³׵᤬ʤ
ĥåȤߤˤʤäƤʤȤϡ
.BR accept ()
³ȯޤǸƤӽФ (block) 롣
åȤߤˤʤäƤơ
Ԥ֤³׵᤬塼̵Ȥϡ
.BR accept ()
ϥ顼
.B EAGAIN

.B EWOULDBLOCK
ǼԤ롣
.PP
åȤؤ³Τˤϡ
.BR select (2)
ޤ
.BR poll (2)
ѤФ褤
³׵᤬ȥåȤɤ߹߲ǽˤʤΤǡ

.BR accept ()
ƤǤ³Ф륽åȤФ褤
뤤ϥåȤԤ餫Υ󤬤äȤ
.B SIGIO
 (deliver) 褦ˤ뤳ȤǤ롣ܺ٤
.BR socket (7)
򻲾ȤΤȡ
.PP
Ū³ǧ (confirmation) ɬפȤ褦ʥץȥ
(DECNet ʤ) Ǥϡ
.BR accept ()
ñ˼³׵򥭥塼ФǤꡢ
³ǧϹԤʤȤդ衣³ǧϡ
ե롦ǥץФ
̾ɤ߼/񤭹ߤˤäƤʤ졢³ (rejection)
ϿåȤ򥯥뤳ȤˤäƤʤ롣
ߤΤȤ
Linux ǤΥޥƥĤΤ DECNet Ǥ롣

.I flags
 0 ξ硢
.BR accept4 ()

.BR accept ()
ƱǤ롣
.I flags
˰ʲͤӥå (OR) ǻꤹ뤳Ȥǡ
ۤʤư򤵤뤳ȤǤ롣
.TP 16
.B SOCK_NONBLOCK
륪ץե뵭 (open file description) 
.B O_NONBLOCK
ե륹ơե饰򥻥åȤ롣
Υե饰ȤȤǡ
.B O_NONBLOCK
򥻥åȤ뤿
.BR fcntl (2)
ɲäǸƤӽФɬפʤʤ롣
.TP
.B SOCK_CLOEXEC
եǥץФ
close-on-exec
.RB ( FD_CLOEXEC )
ե饰򥻥åȤ롣
Υե饰ΩͳˤĤƤϡ
.BR open (2)

.B O_CLOEXEC
ե饰򻲾ȤΤȡ
.SH ֤
硢Υƥॳ
դåȤΥǥץǤ֤ͤ
顼ȯ \-1 ֤
.I errno
Ŭڤꤹ롣
.SS 顼
Linux 
.BR accept ()
(
.BR accept4 ())
ϡåȤˤ롢ȯѤߤΥͥåȥ顼
.BR accept ()
Υ顼ɤȤϤ
ο񤤤 BSD åȤμȤϰۤʤ롣
ι⤤ưԤˤϡ
ץꥱϥץȥƤͥåȥ顼θΤ
.BR accept ()
ΤȤ˹ԤΥ顼
.B EAGAIN
Ʊ褦˰ƻ (retry) Ԥ٤Ǥ롣
TCP/IP ǤϡʲΥ顼:
.BR ENETDOWN ,
.BR EPROTO ,
.BR ENOPROTOOPT ,
.BR EHOSTDOWN ,
.BR ENONET ,
.BR EHOSTUNREACH ,
.BR EOPNOTSUPP ,
.B ENETUNREACH
.SH 顼
.TP
.BR EAGAIN " ޤ " EWOULDBLOCK
.\" Actually EAGAIN on Linux
åȤߤˤʤäƤơ
ļդоݤ³¸ߤʤ
POSIX.1-2001 ϡξˤɤΥ顼֤ȤǧƤꡢ
 2 ĤƱͤĤȤƤʤ
äơܿɬפʥץꥱǤϡξβǽ
ǧ٤Ǥ롣
.TP
.B EBADF
ǥץ
.TP
.B ECONNABORTED
³ߤ줿
.TP
.B EFAULT
.I addr
桼ɥ쥹֤ν񤭹߲ǽΰˤʤ
.TP
.B EINTR
ͭ³夹ª줿ʥˤä
ƥॳ뤬Ǥ줿
.BR signal (7)
ȡ
.TP
.B EINVAL
åȤ³Ԥ֤ǤϤʤ⤷ϡ
.I addrlen
Ǥ (㤨Сξʤ)
.TP
.B EINVAL
.RB ( accept4 ())
.I flags
ͤꤵƤ롣
.TP
.B EMFILE
1ץץǤե롦ǥץξ¤ã
.TP
.B ENFILE
ץ󤵤줿եƥΤξ¤ã
.TP
.BR ENOBUFS ", " ENOMEM
꤬­ʤ
¿ξϡƥ꤬­ʤ櫓ǤϤʤ
åȥХåե礭ˤƤ¤Ǥ롣
.TP
.B ENOTSOCK
ǥץϥåȤǤϤʤե򻲾ȤƤ롣
.TP
.B EOPNOTSUPP
ȤƤ륽åȤη
.B SOCK_STREAM
Ǥʤ
.TP
.B EPROTO
ץȥ롦顼
.PP
嵭˲äơLinux 
.BR accept ()
ϰʲΥ顼ǼԤ:
.TP
.B EPERM
եΥ롼ˤ³ػߤ줿
.PP
¾ˡåȤФͥåȥ顼֤뤳Ȥ⤢롣
Ϥ줾ΥץȥƤ롣
 Linux ͥǤϡ
ʲ˼褦ʥ顼֤Ȥ⤢롣
.BR ENOSR ,
.BR ESOCKTNOSUPPORT ,
.BR EPROTONOSUPPORT ,
.BR ETIMEDOUT .
.B ERESTARTSYS
ȥ졼κ˸뤳Ȥ⤢롣
.SH С
.BR accept4 ()
ƥॳ Linux 2.6.28 ʹߤѲǽǤ롣
glibc ǤΥݡȤϥС 2.10 ʹߤѲǽǤ롣
.SH 
.BR accept ():
POSIX.1-2001,
SVr4, 4.4BSD,
.RB ( accept ()
 4.2BSD ǽƼ줿).
.\" BSD  man ڡˤϡ 5 ĤΥ顼֤줦Ƚ񤫤Ƥ
.\" (EBADF, ENOTSOCK, EOPNOTSUPP, EWOULDBLOCK, EFAULT)
.\" POSIX.1-2001 Ǥϡ
.\" EAGAIN, EBADF, ECONNABORTED, EINTR, EINVAL, EMFILE,
.\" ENFILE, ENOBUFS, ENOMEM, ENOTSOCK, EOPNOTSUPP, EPROTO, EWOULDBLOCK
.\" 顼ȤƵҤƤ롣
.\" ˡSUSv2 ˤ EFAULT, ENOSR ⵭ҤƤ롣

.BR accept4 ()
ɸ Linux ˤĥǤ롣
.LP
Linux Ǥϡ
.BR accept ()
֤åȤ listen ԤäƤ륽åȤ
ե֥ե饰
.RB ( O_NONBLOCK

.B O_ASYNC
ʤ) Ѿ֤ʤס
ưɸŪ BSD åȤμȤϰۤʤäƤ롣
.\" Ĥ¸ȤǤ Tru64 5.1  HP-UX 11 
.\" ե֥ե饰Ѿʤ褦Ǥ롣 -- MTK Jun 05
ܿθץǤϥե֥ե饰Ѿ뤫ɤ
ˤ
.BR accept ()
֤åȤФƤɬפʥե饰Ūꤹ褦
٤Ǥ롣

.SH 
POSIX.1-2001 Ǥ
.I <sys/types.h>
Υ󥯥롼ɤɬܤȤƤ餺
Linux ǤϤΥإåեɬפǤϤʤ
ŪˤϡĤμ (BSD ) ǤΥإåե뤬
ɬפǤꡢܿɬפʥץꥱǤϤΥե
󥯥롼ɤΤǤ

.B SIGIO
Ϥ줿䡢
.BR select (2)
ޤ
.BR poll (2)
ɤ߹߲ǽ٥Ȥ֤ˡ
ɬԵ³Ȥϸ¤ʤ
ʤʤ餽³ϡ
.BR accept ()
ƤФˡƱŪʥͥåȥ顼
¾ΥåɤƤФ줿 (̤) accept ˤä
Ƥ뤫⤷ʤǤ롣
ξ硢
.BR accept ()
ƤӽФ (block) ³ԤĤŤ롣
.BR accept ()
ߤԤ碌ʤ褦ˤˤϡϤå
.I sockfd

.B O_NONBLOCK
ե饰򥻥åȤƤɬפ
.RB ( socket (7)
򸫤)
.SS socklen_t 
.BR accept ()
 3 ϡȤ \fIint *\fP Ƥ
(libc4  libc5, 4.x BSD, SunOS 4, SGI ʤ¿ΥƥǤϤʤäƤ)
POSIX.1g draft ɸϡ
 \fIsize_t *\fP ѹ褦ȤSunOS 5 ǤϤƤ롣
 POSIX drafts ˤ \fIsocklen_t *\fP ޤޤ褦ˤʤꡢ
Single Unix Specification  glibc2 ǤϤΤ褦褦ˤʤä
Linus Torvald ȯѤ:

.\" .I fails: only italicizes a single line
֤ޤȤʥ饤֥ꤿС "socklen_t"
Υ int Ʊˤʤʤʤ
ʤ BSD åؤ˲뤳Ȥˤʤä㤦
POSIX Ϻǽ餳Ĥ size_t ˤǡ
ܤʸ򤬤ʤꤿƤ
(¿ʬͤ¾ˤ⤤Ȼפ¿Ϥʤä褦)
Ĥ size_t ˤΤϴˤƤ롣
㤨 64 ӥåȥƥǤϡ
size_t  "int" ƱʤƤȤϤۤȤɤʤ͡
Υ "int"  ƱǤʤإ٤ʤ
BSD åȥ󥿡եäƤΤϤΤʤ顣
ޤȤ⤫ POSIX οͤ⡢
"socklen_t" ȤʤȤҤͤФ
⤽ǽ餫äƤɤä
ääʾ塢
̾դηʤʤʤȻפäߤ͡
ʤǤϤ狼ʤ
(äȺǽˤäޤäϼʴְ㤤ǴĤ֤ʤä顢
ä̾դؤƼʬ缺Ԥ򤴤ޤȤ)
.SH 
.BR bind (2)
ȡ
.SH Ϣ
.BR bind (2),
.BR connect (2),
.BR listen (2),
.BR select (2),
.BR socket (2),
.BR socket (7)