.\" Copyright (c) 1983, 1990, 1991 The Regents of the University of California.
.\" All rights reserved.
.\"
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.\" modification, are permitted provided that the following conditions
.\" are met:
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.\"    notice, this list of conditions and the following disclaimer.
.\" 2. Redistributions in binary form must reproduce the above copyright
.\"    notice, this list of conditions and the following disclaimer in the
.\"    documentation and/or other materials provided with the distribution.
.\" 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.
.\"
.\"     $Id: recv.2,v 1.5 1999/11/19 15:34:44 hanataka Exp $
.\"
.\" Modified Sat Jul 24 00:22:20 1993 by Rik Faith <faith@cs.unc.edu>
.\" Modified Tue Oct 22 17:45:19 1996 by Eric S. Raymond <esr@thyrsus.com>
.\" Modified 1998,1999 by Andi Kleen
.\"
.\" Japanese Version Copyright (c) 1996 Akira Yoshiyama
.\"         all rights reserved.
.\" Translated Thu Jul 18 01:24:02 JST 1996
.\"         by Akira Yoshiyama <yosshy@jedi.seg.kobe-u.ac.jp>
.\" Modified Sun Dec 14 22:37:11 JST 1997
.\"         by HANATAKA Shinya <hanataka@abyss.rim.or.jp>
.\" Modified Sat Aug 14 10:48:41 JST 1999
.\"         by HANATAKA Shinya <hanataka@abyss.rim.or.jp>
.\"
.TH RECV 2 "Apr 1999" "Linux Man Page" "Linux Programmer's Manual"
.SH ̾
recv, recvfrom, recvmsg \- åȤå
.SH 
.B #include <sys/types.h>
.br
.B #include <sys/socket.h>
.sp
.BI "int recv(int " s ", void *" buf ", size_t " len ", int " flags );
.sp
.BI "int recvfrom(int " s ", void *" buf ", size_t " len ,
.BI "int " flags ", struct sockaddr *" from ", socklen_t *" fromlen );
.sp
.BI "int recvmsg(int " s ", struct msghdr *" msg ", int " flags );
.SH 
.B recvfrom

.B recvmsg
ϥåȤå뤿˻ѤåȤ³ظ
(connection-oriened)ɤ˴ؤ餺åȤΥǡ뤳ȤǤ롣

.I from
 NULL ʳǡåȤ³ظǤʤ 
.I from
˥åΥɥ쥹롣

.I fromlen
ξѤΥѥ᡼ǡǽ
.IR from 
˳ƤХåե礭Ƥ֤äƤˤ
.I from 
˼ºݤ쥢ɥ쥹礭˽֤롣
.PP
.B recv
̾
.I ³줿(connected)
å(
.BR connect (2)
򻲾)ˤĤƤΤ߻Ѥ졢
.I from
ѥ᡼ NULL 
.B recvfrom
Ǥ롣

ˤϻĤΥ롼ϥåĹ֤
åĹ᤮Ϳ줿ХåեǼޤʤäˤ
ååȤμˤäƤ;ʬΥХȤϼΤƤ
⤷ʤ(
.BR socket (2)
򻲾)
.PP
åȤ˼å¸ߤʤä硢ѤΥ
å夹ޤԤġåȤ(nonblocking)
ꤵƤ(
.BR fcntl (2)
򻲾) \-1 ֤ѿ
.I errno

.B EAGAIN
ꤵ롣

̾׵ᤷ̰ʲǼǡ֤
׵̤äѤޤǼޤԤĤȤϤʤư
.BR socket (7)
˵Ҥ줿åؤΥץ
.B SO_RCVLOWAT

.B SO_RCVTIMEO
αƶ롣
.P
.BR select (2)

.BR poll (2)
ϤĥǡϤꤹ뤿˻ѤǤ롣
.PP
recv 
.I flags
ϰʲͤΡİʾ
.I or 
Ǥ:
.TP
.B MSG_OOB
Υե饰̾Υǡȥ꡼ǼǤʤӰ賰(out-of-band)ǡ
뤳Ȥ׵᤹롣̾Υǡ塼Ƭ®ãǡ֤
ץȥ¸ߤ롢ǤΤ褦ʥץȥǤϤΥե饰
ѤǤʤ
.TP
.B MSG_PEEK
Υե饰ϼ塼κǽΥǡ򥭥塼ǡ֤
ˤä³Ʊǡ֤ȤǤ롣
.TP
.B MSG_WAITALL
Υե饰׵ᤷ̤ޤ(block)뤳Ȥ׵᤹롣
ʤ顢ʥμ顼(disconnect)ȯ
˼ǡۤʤ뷿äˤϡ׵ᤷ̤꾯ʤǡ
֤Ȥ롣
.TP
.B MSG_ERRQUEUE
顼塼ѥåȤФ
.TP
.B MSG_NOSIGNAL 
Υեåϥȥ꡼ॽåȤ¦äȯ
.B SIGPIPE
ʥȯʤ褦ˤ롣
.TP
.B MSG_ERRQUEUE
Υե饰ϥ塼줿顼åȤΥ顼塼
褦ˤ롣Υ顼ŪʥåȶϤ롣
.\"  ancilliary  ancillary Υݡ
Ūʥåηϥץȥ˰¸Ƥ롣(IP ξ
.BR IP_RECVERR )
Υ顼
.B sock_extended_err
¤Τ󶡤:
.IP
.RS
.ne 18
.nf
.ta 4n 20n 32n
.\" XXX switch to standard types
#define SO_EE_ORIGIN_NONE      0
#define SO_EE_ORIGIN_LOCAL     1
#define SO_EE_ORIGIN_ICMP      2
#define SO_EE_ORIGIN_ICMP6     3

struct sock_extended_err
{
       __u32   ee_errno;       /* error number */
       __u8    ee_origin;      /* where the error originated */ 
       __u8    ee_type;        /* type */
       __u8    ee_code;        /* code */
       __u8    ee_pad;
       __u32   ee_info;        /* additional information */
       __u32   ee_data;        /* other data */  
};

struct sockaddr *SOCK_EE_OFFENDER(struct sock_extended_err *);
.ta
.fi
.RE
.IP
.B ee_errno 
ˤϥ塼줿顼Υ顼ֹ椬äƤ롣
.B ee_origin
ˤϥ顼ȯΥꥸ󡦥(origin code)äƤ롣
¾Υեɤϥץȥ¸Ǥ롣
.B SOCK_EE_OFFENDER 
ϥ顼ȯͥåȥ֥ȤΥɥ쥹ؤΥݥ󥿡֤
ɥ쥹ξˤ
.B sockaddr 

.I sa_family 
С
.B AF_UNSPEC
ˤʤäƤꡢ¾Υեɤ̤Ǥ롣顼ȯѥå
Ѳ٤̾ΥǡȤϤ롣
.IP
ǤΥ顼ξˤϥɥ쥹Ϥʤ(
.R cmsghdr

.I cmsg_len 
Сǥå뤳ȤǤ)
顼ä硢
.B MSG_ERRQUEUE 
.BR msghdr
ꤵ롣顼Ϥȡ
ڥǥ󥰤Ƥåȡ顼Υ塼줿顼
˴Ťƺƺ졢ΥåκݤϤ롣
.PP
.B recvmsg
ľͿѥ᡼ο򸺤餹
.I msghdr
¤ΤѤ롣ι¤Τ
.IR <sys/socket.h> 
ǰʲΤ褦Ƥ :
.IP
.RS
.nf
.ta 4n 17n 33n
struct msghdr {
	void	* msg_name;	/* optional address */
	socklen_t	msg_namelen;	/* size of address */
	struct iovec	* msg_iov;	/* scatter/gather array */
	size_t	msg_iovlen;	/* # elements in msg_iov */
	void	* msg_control;	/* ancillary data, see below */
	socklen_t	msg_controllen;	/* ancillary data buffer len */
	int	msg_flags;	/* flags on received message */
};
.ta
.fi
.RE
.PP

.I msg_name

.I msg_namelen
ϥåȤ³ƤʤˡΥɥ쥹Ǽ롣
̾ɬפʤˤ
.I msg_name
 NULL 뤳ȤǤ롣
.I msg_iov

.I msg_iovlen
եɤ
.BR readv (2)
˵ҤƤ褦/ѤΥ٥ꤹ롣
.IR msg_control 
եɤ
.IR msg_controllen
Ĺ¾ΥåϢΥץȥ椹Хåե
¾ŪʥǡΤΥХåեؤΥݥ󥿡Ǥ롣
.B recvmsg 
ƤФ줿
.I msg_controllen

.I msg_control
ѲǽʥХåեĹäƤɬפ롣
뤫֤äƤ硢åĹäƤ롣
.PP
åη:
.PP
.RS
.nf
.ta 4n 16n 28n
struct cmsghdr {
	socklen_t	cmsg_len;	/* data byte count, including hdr */
	int	cmsg_level;	/* originating protocol */
	int	cmsg_type;	/* protocol-specific type */
/* followed by
	u_char	cmsg_data[]; */
};
.ta
.fi
.RE
.PP
Ūʥǡ
.BR cmsg (3)
줿ޥǤΤߥ٤Ǥ롣
.PP
ȤơLinux ϤŪǡΥᥫ˥ĥ顼
IP ץ䡢Unix åȴ֤ǥե롦ǥץ
ϤΤ˻Ѥ롣
.PP
.I msg_flags
եɤϼå򻲾Ȥ褦ֵѻꤵ롣
.B MSG_EOR
ϥ쥳ɤν(end-of-record)򼨤Υǡϴʥ쥳ɤ
֤Ȥ򼨤(Ūˤ
.BR SOCK_SEQPACKET 
ΥåȤǻѤ)
.B MSG_TRUNC
ϡǡबͿ줿Хåե礭ä
ǡΤϤ߽ФʬΤƤ줿Ȥ򼨤
.B MSG_CTRUNC
ŪʥǡΤΥХåե­ˡǡΰ
ΤƤ줿򼨤
®ãǡӰ賰ǡȤ򼨤
.B MSG_OOB
֤롣
.B MSG_ERRQUEUE
ϥǡƤʤåȤΥ顼塼ĥ顼
Ȥ򼨤
.SH ֤
ΥϼХȿ֤顼ξ \-1 ֤롣
.SH 顼
ϥåؤȯŪʥ顼Ǥ롣ؤ
ץȥ롦⥸塼뤫֤¾Υ顼뤫⤷ʤ
Υޥ˥奢򻲾Ȥ뤳ȡ
.TP 0.8i
.B EBADF

.I s
̵ʥǥץǤ롣
.TP
.B ENOTCONN
åȤ³ظץȥ뤬ƤƤꡢ
ޤ³Ƥʤ(
.BR connect (2)

.BR accept (2)
򻲾Ȥ뤳)
.TP
.B ENOTSOCK

.I s
åȤ򻲾ȤƤʤ
.TP
.B EAGAIN
åȤ(non-blocking)ꤵƤߤ
˻ڤ(timeout)ꤵƤꡢǡ
ڤˤʤä
.TP
.B EINTR
ǡ˥ʥ(signal)Ƴޤ줿
.TP
.B EFAULT
ХåեؤΥݥ󥿡ץΥɥ쥹ֳؤƤ롣
.TP
.B EINVAL
̵ʰϤ줿
.SH 
4.4BSD (δؿ 4.2BSD Ǹ줿)
.SH 
嵭Υץȥפ glibc2 ˤäƤ롣
Single Unix Specification Ǥ ssize_t ֤ȤƱͤǤ롣
( BSD 4.*  libc4  libc5  `int' ѤƤ)
.I flags
 BSD 4.* Ǥ `int' libc4  libc5 Ǥ `unsigned int' Ǥ롣
.I len
 BSD 4.* Ǥ `int'  libc4  libc5 Ǥ `size_t' Ǥ롣
.I fromlen
 BSD 4.*, libc4, libc5 Ǥ `int *' Ǥ롣
ߤ `socklen_t *'  POSIX ȯ줿
.BR accept (2)
⻲Ȥ뤳ȡ
.SH Ϣ
.BR fcntl (2),
.BR read (2),
.BR select (2),
.BR getsockopt (2), 
.BR socket (2), 
.BR cmsg (3)