[linuxjm/LDP_man-pages.git] / draft / man2 / msgop.2

.\" Copyright 1993 Giorgio Ciucci <giorgio@crcc.it>
.\"
.\" Permission is granted to make and distribute verbatim copies of this
.\" manual provided the copyright notice and this permission notice are
.\" preserved on all copies.
.\"
.\" Permission is granted to copy and distribute modified versions of this
.\" manual under the conditions for verbatim copying, provided that the
.\" entire resulting derived work is distributed under the terms of a
.\" permission notice identical to this one.
.\"
.\" Since the Linux kernel and libraries are constantly changing, this
.\" manual page may be incorrect or out-of-date.  The author(s) assume no
.\" responsibility for errors or omissions, or for damages resulting from
.\" the use of the information contained herein.  The author(s) may not
.\" have taken the same level of care in the production of this manual,
.\" which is licensed free of charge, as they might when working
.\" professionally.
.\"
.\" Formatted or processed versions of this manual, if unaccompanied by
.\" the source, must acknowledge the copyright and authors of this work.
.\"
.\" Modified Tue Oct 22 16:40:11 1996 by Eric S. Raymond <esr@thyrsus.com>
.\" Modified Mon Jul 10 21:09:59 2000 by aeb
.\" Modified 1 Jun 2002, Michael Kerrisk <mtk.manpages@gmail.com>
.\"     Language clean-ups.
.\"     Enhanced and corrected information on msg_qbytes, MSGMNB and MSGMAX
.\"     Added note on restart behavior of msgsnd() and msgrcv()
.\"     Formatting clean-ups (argument and field names marked as .I
.\"             instead of .B)
.\" Modified, 27 May 2004, Michael Kerrisk <mtk.manpages@gmail.com>
.\"     Added notes on capability requirements
.\" Modified, 11 Nov 2004, Michael Kerrisk <mtk.manpages@gmail.com>
.\"     Language and formatting clean-ups
.\"     Added notes on /proc files
.\" FIXME . Add example programs to this page.
.\"
.\" Japanese Version Copyright (c) 1997 HANATAKA Shinya
.\"         all rights reserved.
.\" Translated 1997-02-23, HANATAKA Shinya <hanataka@abyss.rim.or.jp>
.\" Modified 2000-09-23, HANATAKA Shinya <hanataka@abyss.rim.or.jp>
.\" Updated 2002-11-26, Kentaro Shirakata <argrath@ub32.org>
.\" Updated 2005-03-04, Akihiro MOTOKI <amotoki@dd.iij4u.or.jp>
.\" Updated 2006-03-05, Akihiro MOTOKI, LDP v2.25
.\" Updated 2008-08-09, Akihiro MOTOKI, LDP v3.05
.\"
.\"WORD:        message                 ¥á¥Ã¥»¡¼¥¸
.\"WORD:        operation               Áàºî
.\"WORD:        queue                   ¥­¥å¡¼
.\"WORD:        process                 ¥×¥í¥»¥¹
.\"WORD:        catch                   Êá³Í(catch)
.\"WORD:        signal                  ¥·¥°¥Ê¥ë
.\"WORD:        suspend                 Ää»ß(suspend)
.\"WORD:        sleep                   Ää»ß(sleep)
.\"WORD:        block                   Ää»ß(block)
.\"WORD:        process-ID              ¥×¥í¥»¥¹ID
.\"WORD:        type                    ·¿
.\"WORD:        policy                  Êý¿Ë
.\"WORD:        super-user              ¥¹¡¼¥Ñ¡¼¡¦¥æ¡¼¥¶¡¼
.\"WORD:        current time            ¸½ºß»þ¹ï
.\"WORD:        implement               ¼ÂÁõ
.\"
.TH MSGOP 2 2008-04-23 "Linux" "Linux Programmer's Manual"
.\"O .SH NAME
.SH ̾Á°
.\"O msgrcv, msgsnd \- message operations
msgrcv, msgsnd \- ¥á¥Ã¥»¡¼¥¸Áàºî
.\"O .SH SYNOPSIS
.SH ½ñ¼°
.nf
.B #include <sys/types.h>
.B #include <sys/ipc.h>
.B #include <sys/msg.h>
.sp
.BI "int msgsnd(int " msqid ", const void *" msgp ", size_t " msgsz \
", int " msgflg );
.sp
.BI "ssize_t msgrcv(int " msqid ", void *" msgp ", size_t " msgsz \
", long " msgtyp ,
.BI "               int " msgflg );
.fi
.\"O .SH DESCRIPTION
.SH ÀâÌÀ
.\"O The
.\"O .BR msgsnd ()
.\"O and
.\"O .BR msgrcv ()
.\"O system calls are used, respectively, to send messages to,
.\"O and receive messages from, a message queue.
.\"O The calling process must have write permission on the message queue
.\"O in order to send a message, and read permission to receive a message.
¥·¥¹¥Æ¥à¥³¡¼¥ë
.BR msgsnd ()
¤È
.BR msgrcv ()
¤Ï¤½¤ì¤¾¤ì¡¢¥á¥Ã¥»¡¼¥¸¡¦¥­¥å¡¼¤Ø¤Î¥á¥Ã¥»¡¼¥¸¤ÎÁ÷¿®¤È¡¢
¥á¥Ã¥»¡¼¥¸¤Î¼õ¿®¤Ë»ÈÍѤµ¤ì¤ë¡£¸Æ¤Ó½Ð¤·¸µ¥×¥í¥»¥¹¤Ï¡¢
¥á¥Ã¥»¡¼¥¸¤òÁ÷¿®¤¹¤ë¤¿¤á¤Ë¤Ï¥á¥Ã¥»¡¼¥¸¡¦¥­¥å¡¼¤ËÂФ¹¤ë½ñ¤­¹þ¤ßµö²Ä¤ò¡¢
¥á¥Ã¥»¡¼¥¸¤ò¼õ¿®¤¹¤ë¤¿¤á¤Ë¤ÏÆɤ߽Ф·µö²Ä¤ò»ý¤Ã¤Æ¤¤¤Ê¤±¤ì¤Ð¤Ê¤é¤Ê¤¤¡£
.PP
.\"O The
.\"O .I msgp
.\"O argument is a pointer to caller-defined structure
.\"O of the following general form:
¸Æ¤Ó½Ð¤·¸µ¥×¥í¥»¥¹¤Ï°Ê²¼¤Ë¼¨¤¹¹½Â¤ÂΤòÍÑ°Õ¤·¡¢¤³¤Î¹½Â¤ÂΤؤÎ
¥Ý¥¤¥ó¥¿¤ò
.msgp
°ú¤­¿ô¤È¤·¤ÆÅϤ¹¡£
.in +4n
.nf

struct msgbuf {
    long mtype;       /* message type, must be > 0 */
    char mtext[1];    /* message data */
};
.fi
.in
.PP
.\"O The
.\"O .I mtext
.\"O field is an array (or other structure) whose size is specified by
.\"O .IR msgsz ,
.\"O a nonnegative integer value.
.I mtext
¥Õ¥£¡¼¥ë¥É¤ÏÇÛÎó (¤Þ¤¿¤Ï¾¤Î¹½Â¤ÂÎ) ¤Ç¡¢¤½¤ÎÂ礭¤µ¤Ï
ÈóÉé¤ÎÀ°¿ô¤Ç¤¢¤ë
.I msgsz
¤Ç»ØÄꤵ¤ì¤ë¡£
.\"O Messages of zero length (i.e., no
.\"O .I mtext
.\"O field) are permitted.
Ťµ 0 ¤Î¥á¥Ã¥»¡¼¥¸ (¤Ä¤Þ¤ê
.I mtext
¥Õ¥£¡¼¥ë¥É¤¬¤Ê¤¤¥á¥Ã¥»¡¼¥¸) ¤âǧ¤á¤é¤ì¤Æ¤¤¤ë¡£
.\"O The
.\"O .I mtype
.\"O field must have a strictly positive integer value.
.\"O This value can be
.\"O used by the receiving process for message selection
.\"O (see the description of
.\"O .BR msgrcv ()
.\"O below).
.B mtype
¥Õ¥£¡¼¥ë¥É¤Ï¸·Ì©¤ËÀµ¤ÎÀ°¿ô¤Ç¤Ê¤±¤ì¤Ð¤Ê¤é¤Ê¤¤¡£
¤³¤ÎÃͤϡ¢¥á¥Ã¥»¡¼¥¸¤ò¼õ¿®¤¹¤ë¥×¥í¥»¥¹¤Ç¥á¥Ã¥»¡¼¥¸¤òÁªÂò¤¹¤ë¤¿¤á¤Ë
»ÈÍѤµ¤ì¤ë (²¼µ­¤Î
.BR msgrcv ()
¤ÎÀâÌÀ¤ò»²¾È¤Î¤³¤È)¡£
.SS msgsnd()
.\"O The
.\"O .BR msgsnd ()
.\"O system call appends a copy of the message pointed to by
.\"O .I msgp
.\"O to the message queue whose identifier is specified
.\"O by
.\"O .IR msqid .
.BR msgsnd ()
¥·¥¹¥Æ¥à¥³¡¼¥ë¤Ï
.I msgp
°ú¤­¿ô¤Ç»ØÄꤵ¤ì¤¿¥á¥Ã¥»¡¼¥¸¤Î¥³¥Ô¡¼¤ò
.I msqid
¤Ç»ØÄꤵ¤ì¤¿¼±Ê̻Ҥò»ý¤Ä¥á¥Ã¥»¡¼¥¸¡¦¥­¥å¡¼¤ØÄɲ乤롣
.PP
.\"O If sufficient space is available in the queue,
.\"O .BR msgsnd ()
.\"O succeeds immediately.
¥­¥å¡¼¤Ë½½Ê¬¤Ê¶õ¤­ÍÆÎ̤¬¤¢¤ë¾ì¹ç¡¢
.BR msgsnd ()
¤Ïľ¤Á¤ËÀ®¸ù¤¹¤ë¡£
.\"O (The queue capacity is defined by the
.\"O .I msg_bytes
.\"O field in the associated data structure for the message queue.
.\"O During queue creation this field is initialized to
.\"O .B MSGMNB
.\"O bytes, but this limit can be modified using
.\"O .BR msgctl (2).)
(¥­¥å¡¼¤ÎÍÆÎ̤ϡ¢¥á¥Ã¥»¡¼¥¸¡¦¥­¥å¡¼¤Î¥Ç¡¼¥¿¹½Â¤ÂΤÎ
.I msg_bytes
¥Õ¥£¡¼¥ë¥É¤ÇÄêµÁ¤µ¤ì¤ë¡£
¥­¥å¡¼ºîÀ®»þ¤Ë¤³¤Î¥Õ¥£¡¼¥ë¥É¤Ï
.B MSGMNB
¤Ë½é´ü²½¤µ¤ì¤ë¤¬¡¢¤³¤ÎÀ©¸Â¤Ï
.BR msgctl (2)
¤ò»È¤Ã¤ÆÊѹ¹¤Ç¤­¤ë¡£)
.\"O If insufficient space is available in the queue, then the default
.\"O behavior of
.\"O .BR msgsnd ()
.\"O is to block until space becomes available.
¥­¥å¡¼¤Ë½½Ê¬¤Ê¶õ¤­ÍÆÎ̤¬¤Ê¤¤¾ì¹ç¡¢
¥Ç¥Õ¥©¥ë¥È¤Ç¤Ï
.BR msgsnd ()
¤Ï¶õ¤­ÍÆÎ̤¬¤Ç¤­¤ë¤Þ¤ÇÄä»ß (block) ¤¹¤ë¡£
.\"O If
.\"O .B IPC_NOWAIT
.\"O is specified in
.\"O .IR msgflg ,
.\"O then the call instead fails with the error
.\"O .BR EAGAIN .
.I msgflg
¤Ë
.B IPC_NOWAIT
¤¬»ØÄꤵ¤ì¤¿¾ì¹ç¤Ï¡¢¥¨¥é¡¼
.B EAGAIN
¤Ç¼ºÇÔ¤¹¤ë¡£

.\"O A blocked
.\"O .BR msgsnd ()
.\"O call may also fail if:
Ää»ß¤·¤Æ¤¤¤ë
.BR msgsnd ()
¤Ï°Ê²¼¤Î¾ì¹ç¤Ë¤â¼ºÇÔ¤¹¤ë¡£
.IP * 2
.\"O the queue is removed,
.\"O in which case the system call fails with
.\"O .I errno
.\"O set to
.\"O .BR EIDRM ;
.\"O or
¥­¥å¡¼¤¬ºï½ü¤µ¤ì¤¿¡£
¤³¤Î¾ì¹ç¡¢
.I errno
¤Ï
.B EIDRM
¤ËÀßÄꤵ¤ì¤ë¡£
.IP *
.\"O a signal is caught, in which case the system call fails
.\"O with
.\"O .I errno
.\"O set to
.\"O .BR EINTR ; see
.\"O .BR signal (7).
¥·¥°¥Ê¥ë¤¬Ê᪤µ¤ì¤¿¡£
¤³¤Î¾ì¹ç¡¢
.I errno
¤Ï
.BR EINTR
¤ËÀßÄꤵ¤ì¤ë¡£
.BR signal (7)
»²¾È¡£
.\"O .RB ( msgsnd ()
.\"O is never automatically restarted after being interrupted by a
.\"O signal handler, regardless of the setting of the
.\"O .B SA_RESTART
.\"O flag when establishing a signal handler.)
.RB ( msgsnd ()
¤Ï¡¢¤¿¤È¤¨¥·¥°¥Ê¥ë¥Ï¥ó¥É¥é¤ÎÀßÄê»þ¤Ë
.B SA_RESTART
¤ò»ØÄꤷ¤Æ¤¤¤¿¤È¤·¤Æ¤â¡¢¥·¥°¥Ê¥ë¥Ï¥ó¥É¥é¤Ë¤è¤Ã¤Æ³ä¤ê¹þ¤Þ¤ì¤¿¸å¤Ç
¼«Æ°Åª¤ËºÆ¥¹¥¿¡¼¥È¤¹¤ë¤³¤È¤Ï·è¤·¤Æ¤Ê¤¤¡£)
.PP
.\"O Upon successful completion the message queue data structure is updated
.\"O as follows:
Àµ¾ï¤Ë½ªÎ»¤·¤¿¾ì¹ç¡¢¥á¥Ã¥»¡¼¥¸¡¦¥­¥å¡¼¤Î¥Ç¡¼¥¿¹½Â¤ÂΤϰʲ¼¤Î¤è¤¦¤Ë
¹¹¿·¤µ¤ì¤ë:
.IP
.\"O .I msg_lspid
.\"O is set to the process ID of the calling process.
.I msg_lspid
¤Ë¤Ï¸Æ¤Ó½Ð¤·¸µ¥×¥í¥»¥¹¤Î¥×¥í¥»¥¹ ID ¤¬ÀßÄꤵ¤ì¤ë¡£
.IP
.\"O .I msg_qnum
.\"O is incremented by 1.
.I msg_qnum
¤Ï 1 Áý²Ã¤¹¤ë¡£
.IP
.\"O .I msg_stime
.\"O is set to the current time.
.I msg_stime
¤Ë¤Ï¸½ºß»þ¹ï¤¬ÀßÄꤵ¤ì¤ë¡£
.SS msgrcv()
.\"O The
.\"O .BR msgrcv ()
.\"O system call removes a message from the queue specified by
.\"O .I msqid
.\"O and places it in the buffer
.\"O pointed to by
.\"O .IR msgp .
.BR msgrcv ()
¥·¥¹¥Æ¥à¥³¡¼¥ë¤Ï
.I msqid
¤Ç»ØÄꤵ¤ì¤¿¥­¥å¡¼¤«¤é¥á¥Ã¥»¡¼¥¸¤òºï½ü¤·¡¢
.I msgp
¤Ç»ØÄꤵ¤ì¤¿¥Ð¥Ã¥Õ¥¡¤Ë¤½¤Î¥á¥Ã¥»¡¼¥¸¤ò³ÊǼ¤¹¤ë¡£
.PP
.\"O The argument
.\"O .I msgsz
.\"O specifies the maximum size in bytes for the member
.\"O .I mtext
.\"O of the structure pointed to by the
.\"O .I msgp
.\"O argument.
.I msgsz
°ú¤­¿ô¤Ë¤Ï
.I msgp
°ú¤­¿ô¤Ç»ØÄꤵ¤ì¤¿¹½Â¤ÂΤÎ
.I mtext
¥á¥ó¥Ð¡¼¤ÎºÇÂç¤Î¥Ð¥¤¥È¿ô¤ò»ØÄꤹ¤ë¡£
.\"O If the message text has length greater than
.\"O .IR msgsz ,
.\"O then the behavior depends on whether
.\"O .B MSG_NOERROR
.\"O is specified in
.\"O .IR msgflg .
.\"O If
.\"O .B MSG_NOERROR
.\"O is specified, then
.\"O the message text will be truncated (and the truncated part will be
.\"O lost); if
.\"O .B MSG_NOERROR
.\"O is not specified, then
.\"O the message isn't removed from the queue and
.\"O the system call fails returning \-1 with
.\"O .I errno
.\"O set to
.\"O .BR E2BIG .
¥á¥Ã¥»¡¼¥¸¤Î¥Æ¥­¥¹¥È¤ÎŤµ¤¬
.I msgsz
¤è¤êÂ礭¤¤¾ì¹ç¤ÎÆ°ºî¤Ï¡¢
.I msgflg
¤Ë
.B MSG_NOERROR
¤¬»ØÄꤵ¤ì¤Æ¤¤¤ë¤«¤É¤¦¤«¤Ç·è¤Þ¤ë¡£
.B MSG_NOERROR
¤¬»ØÄꤵ¤ì¤Æ¤¤¤ì¤Ð¡¢¥á¥Ã¥»¡¼¥¸¤Î¥Æ¥­¥¹¥È¤ÏÀÚ¤êµÍ¤á¤é¤ì¤ë
(ÀÚ¤ê¼Î¤Æ¤é¤ì¤¿Éôʬ¤Ï¼º¤ï¤ì¤ë)¡£
.B MSG_NOERROR
¤¬»ØÄꤵ¤ì¤Æ¤¤¤Ê¤±¤ì¤Ð¡¢¥á¥Ã¥»¡¼¥¸¤Ï¥­¥å¡¼¤«¤éºï½ü¤µ¤ì¤º¡¢
¥·¥¹¥Æ¥à¥³¡¼¥ë¤Ï \-1 ¤òÊÖ¤·¤Æ¼ºÇÔ¤·¡¢
.I errno
¤Ë
.B E2BIG
¤¬ÀßÄꤵ¤ì¤ë¡£
.PP
.\"O The argument
.\"O .I msgtyp
.\"O specifies the type of message requested as follows:
.I msgtyp
°ú¤­¿ô¤Ë¤ÏÍ׵᤹¤ë¥á¥Ã¥»¡¼¥¸¤Î·¿¤ò»ØÄꤹ¤ë¡£
·¿¤Ï°Ê²¼¤Î¤è¤¦¤Ë»ØÄꤹ¤ë:
.IP * 2
.\"O If
.\"O .I msgtyp
.\"O is 0,
.\"O then the first message in the queue is read.
.I msgtyp
¤¬ 0 ¤Ê¤é¤Ð¡¢¥­¥å¡¼¤ÎºÇ½é¤Ë¤¢¤ë¥á¥Ã¥»¡¼¥¸¤¬Æɤ߹þ¤Þ¤ì¤ë¡£
.IP *
.\"O If
.\"O .I msgtyp
.\"O is greater than 0,
.\"O then the first message in the queue of type
.\"O .I msgtyp
.\"O is read, unless
.\"O .B MSG_EXCEPT
.\"O was specified in
.\"O .IR msgflg ,
.\"O in which case
.\"O the first message in the queue of type not equal to
.\"O .I msgtyp
.\"O will be read.
.I msgtyp
¤¬ 0 ¤è¤êÂ礭¤¤¾ì¹ç¡¢
.I msgflg
¤Ë
.B MSG_EXCEPT
¤¬»ØÄꤵ¤ì¤Æ¤¤¤Ê¤±¤ì¤Ð¡¢
.I msgtyp
·¿¤Î¥­¥å¡¼¤ÎºÇ½é¤Î¥á¥Ã¥»¡¼¥¸¤¬Æɤ߹þ¤Þ¤ì¤ë¡£
.B MSG_EXCEPT
¤¬»ØÄꤵ¤ì¤¿¾ì¹ç¤Ï¡¢
.I msgtyp
·¿°Ê³°¤Î¥­¥å¡¼¤ÎºÇ½é¤Î¥á¥Ã¥»¡¼¥¸¤¬Æɤ߹þ¤Þ¤ì¤ë¡£
.IP *
.\"O If
.\"O .I msgtyp
.\"O is less than 0,
.\"O then the first message in the queue with the lowest type less than or
.\"O equal to the absolute value of
.\"O .I msgtyp
.\"O will be read.
.I msgtyp
¤¬ 0 ¤è¤ê¾®¤µ¤±¤ì¤Ð¡¢
.I msgtyp
¤ÎÀäÂÐÃͰʲ¼¤ÇºÇ¤â¾®¤µ¤¤·¿¤ò»ý¤Ä¥­¥å¡¼¤ÎºÇ½é¤Î¥á¥Ã¥»¡¼¥¸¤¬Æɤ߹þ¤Þ¤ì¤ë¡£
.PP
.\"O The
.\"O .I msgflg
.\"O argument is a bit mask constructed by ORing together zero or more
.\"O of the following flags:
.I msgflg
°ú¤­¿ô¤Ë¤Ï¡¢°Ê²¼¤Î¥Õ¥é¥°¤òǤ°Õ¤Î¿ô¤À¤± (0¸Ä¤â²Ä)¡¢¤³¤ì¤é¤Î OR ¤Ç»ØÄꤹ¤ë:
.TP
.B IPC_NOWAIT
.\"O Return immediately if no message of the requested type is in the queue.
.\"O The system call fails with
.\"O .I errno
.\"O set to
.\"O .BR ENOMSG .
¥­¥å¡¼¤ËÍ׵ᤵ¤ì¤¿·¿¤Î¥á¥Ã¥»¡¼¥¸¤¬¤Ê¤¤¾ì¹ç¤Ë¤Ïľ¤Á¤ËÊ֤롣
¥·¥¹¥Æ¥à¥³¡¼¥ë¤Ï¼ºÇÔ¤·¡¢
.I errno
¤Ë¤Ï
.B ENOMSG
¤¬ÀßÄꤵ¤ì¤ë¡£
.TP
.B MSG_EXCEPT
.\"O Used with
.\"O .I msgtyp
.\"O greater than 0
.\"O to read the first message in the queue with message type that differs
.\"O from
.\"O .IR msgtyp .
0 ¤è¤êÂ礭¤Ê
.I msgtyp
¤È°ì½ï¤Ë»ÈÍѤ·¤Æ¡¢
.I msgtyp
°Ê³°¤Î¥­¥å¡¼¤ÎºÇ½é¤Î¥á¥Ã¥»¡¼¥¸¤òÆɤ߹þ¤à¡£
.TP
.B MSG_NOERROR
.\"O To truncate the message text if longer than
.\"O .I msgsz
.\"O bytes.
.I msgsz
¥Ð¥¤¥È¤è¤ê¤âŤ«¤Ã¤¿¾ì¹ç¤Ï¥á¥Ã¥»¡¼¥¸¤Î¥Æ¥­¥¹¥È¤òÀÚ¤êµÍ¤á¤ë¡£
.PP
.\"O If no message of the requested type is available and
.\"O .B IPC_NOWAIT
.\"O isn't specified in
.\"O .IR msgflg ,
.\"O the calling process is blocked until one of the following conditions occurs:
Í׵ᤵ¤ì¤¿·¿¤Î¥á¥Ã¥»¡¼¥¸¤¬Â¸ºß¤»¤º¡¢
.I msgflg
¤Ë
.B IPC_NOWAIT
¤¬»ØÄꤵ¤ì¤Æ¤¤¤Ê¤«¤Ã¤¿¾ì¹ç¡¢¸Æ¤Ó½Ð¤·¸µ¥×¥í¥»¥¹¤Ï
°Ê²¼¤Î¤¤¤º¤ì¤«¤Î¾õ¶·¤Ë¤Ê¤ë¤Þ¤ÇÄä»ß (block) ¤µ¤ì¤ë:
.IP * 2
.\"O A message of the desired type is placed in the queue.
Í׵ᤷ¤Æ¤¤¤ë·¿¤Î¥á¥Ã¥»¡¼¥¸¤¬¥­¥å¡¼¤ØÆþ¤ì¤é¤ì¤¿¡£
.IP *
.\"O The message queue is removed from the system.
.\"O In this case the system call fails with
.\"O .I errno
.\"O set to
.\"O .BR EIDRM .
¥á¥Ã¥»¡¼¥¸¡¦¥­¥å¡¼¤¬¥·¥¹¥Æ¥à¤«¤éºï½ü¤µ¤ì¤¿¡£
¤³¤Î¾ì¹ç¡¢¥·¥¹¥Æ¥à¥³¡¼¥ë¤Ï¼ºÇÔ¤·¡¢
.I errno
¤Ë
.B EIDRM
¤¬ÀßÄꤵ¤ì¤ë¡£
.IP *
.\"O The calling process catches a signal.
.\"O In this case the system call fails with
.\"O .I errno
.\"O set to
.\"O .BR EINTR .
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¤³¤Î¾ì¹ç¡¢¥·¥¹¥Æ¥à¥³¡¼¥ë¤Ï¼ºÇÔ¤·¡¢
.I errno
¤Ë
.B EINTR
¤¬ÀßÄꤵ¤ì¤ë¡£
.\"O .RB ( msgrcv ()
.\"O is never automatically restarted after being interrupted by a
.\"O signal handler, regardless of the setting of the
.\"O .B SA_RESTART
.\"O flag when establishing a signal handler.)
.RB ( msgrcv ()
¤Ï¡¢¤¿¤È¤¨¥·¥°¥Ê¥ë¥Ï¥ó¥É¥é¤ÎÀßÄê»þ¤Ë
.B SA_RESTART
¤ò»ØÄꤷ¤Æ¤¤¤¿¤È¤·¤Æ¤â¡¢¥·¥°¥Ê¥ë¥Ï¥ó¥É¥é¤Ë¤è¤Ã¤Æ³ä¤ê¹þ¤Þ¤ì¤¿¸å¤Ç
¼«Æ°Åª¤ËºÆ¥¹¥¿¡¼¥È¤¹¤ë¤³¤È¤Ï·è¤·¤Æ¤Ê¤¤¡£)
.PP
.\"O Upon successful completion the message queue data structure is updated
.\"O as follows:
¼Â¹Ô¤ËÀ®¸ù¤·¤¿¾ì¹ç¡¢¥á¥Ã¥»¡¼¥¸¡¦¥­¥å¡¼¤Î¥Ç¡¼¥¿¹½Â¤ÂΤϰʲ¼¤Î¤è¤¦¤Ë
¹¹¿·¤µ¤ì¤ë:
.IP
.\"O .I msg_lrpid
.\"O is set to the process ID of the calling process.
.I msg_lrpid
¤Ë¤Ï¸Æ¤Ó½Ð¤·¸µ¥×¥í¥»¥¹¤Î¥×¥í¥»¥¹ ID ¤¬ÀßÄꤵ¤ì¤ë¡£
.IP
.\"O .I msg_qnum
.\"O is decremented by 1.
.I msg_qnum
¤Ï 1 ¸º»»¤µ¤ì¤ë¡£
.IP
.\"O .I msg_rtime
.\"O is set to the current time.
.I msg_rtime
¤Ë¤Ï¸½ºß¤Î»þ¹ï¤¬ÀßÄꤵ¤ì¤ë¡£
.\"O .SH "RETURN VALUE"
.SH ÊÖ¤êÃÍ
.\"O On failure both functions return \-1
.\"O with
.\"O .I errno
.\"O indicating the error,
.\"O otherwise
.\"O .BR msgsnd ()
.\"O returns 0
.\"O and
.\"O .BR msgrcv ()
.\"O returns the number of bytes actually copied into the
.\"O .I mtext
.\"O array.
¼ºÇÔ¤·¤¿¾ì¹ç¤Ï¡¢¤É¤Á¤é¤Î´Ø¿ô¤â \-1 ¤òÊÖ¤·¡¢¥¨¥é¡¼¤ò
.I errno
¤Ëɽ¼¨¤¹¤ë¡£À®¸ù¤·¤¿¾ì¹ç¡¢
.BR msgsnd ()
¤Ï 0 ¤òÊÖ¤·¡¢
.BR msgrcv ()
¤Ï
.I mtext
ÇÛÎó¤Ë¼ÂºÝ¤Ë¥³¥Ô¡¼¤·¤¿¥Ð¥¤¥È¿ô¤òÊÖ¤¹¡£
.\"O .SH ERRORS
.SH ¥¨¥é¡¼
.\"O When
.\"O .BR msgsnd ()
.\"O fails,
.\"O .I errno
.\"O will be set to one among the following values:
.BR msgsnd ()
¤¬¼ºÇÔ¤·¤¿¾ì¹ç¡¢
.B errno
¤Ë°Ê²¼¤ÎÃͤΤ¤¤º¤ì¤«¤¬ÀßÄꤵ¤ì¤ë:
.TP
.B EACCES
.\"O The calling process does not have write permission on the message queue,
.\"O and does not have the
.\"O .B CAP_IPC_OWNER
.\"O capability.
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.B CAP_IPC_OWNER
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.B EAGAIN
.\"O The message can't be sent due to the
.\"O .I msg_qbytes
.\"O limit for the queue and
.\"O .B IPC_NOWAIT
.\"O was specified in
.\"O .IR msgflg .
.I msg_qbytes
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.I msgflg
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.B IPC_NOWAIT
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.B EFAULT
.\"O The address pointed to by
.\"O .I msgp
.\"O isn't accessible.
.I msgp
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.B EIDRM
.\"O The message queue was removed.
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.B EINTR
.\"O Sleeping on a full message queue condition, the process caught a signal.
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.B EINVAL
.\"O Invalid
.\"O .I msqid
.\"O value, or nonpositive
.\"O .I mtype
.\"O value, or
.\"O invalid
.\"O .I msgsz
.\"O value (less than 0 or greater than the system value
.\"O .BR MSGMAX ).
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.B MSGMAX
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.B ENOMEM
.\"O The system does not have enough memory to make a copy of the
.\"O message pointed to by
.\"O .IR msgp .
.I msgp
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.\"O When
.\"O .BR msgrcv ()
.\"O fails,
.\"O .I errno
.\"O will be set to one among the following values:
.BR msgrcv ()
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.I errno
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.B E2BIG
.\"O The message text length is greater than
.\"O .I msgsz
.\"O and
.\"O .B MSG_NOERROR
.\"O isn't specified in
.\"O .IR msgflg .
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.B EACCES
.\"O The calling process does not have read permission on the message queue,
.\"O and does not have the
.\"O .B CAP_IPC_OWNER
.\"O capability.
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.B CAP_IPC_OWNER
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.B EAGAIN
.\"O No message was available in the queue and
.\"O .B IPC_NOWAIT
.\"O was specified in
.\"O .IR msgflg .
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.B EFAULT
.\"O The address pointed to by
.\"O .I msgp
.\"O isn't accessible.
.I msgp
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.B EIDRM
.\"O While the process was sleeping to receive a message,
.\"O the message queue was removed.
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.B EINTR
.\"O While the process was sleeping to receive a message,
.\"O the process caught a signal; see
.\"O .BR signal (7).
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.BR signal (7)
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.B EINVAL
.\"O .I msgqid
.\"O was invalid, or
.\"O .I msgsz
.\"O was less than 0.
.I msgqid
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.B ENOMSG
.\"O .B IPC_NOWAIT
.\"O was specified in
.\"O .I msgflg
.\"O and no message of the requested type existed on the message queue.
.I msgflg
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.\"O .SH "CONFORMING TO"
.SH ½àµò
SVr4, POSIX.1-2001.
.\"O .SH NOTES
.SH Ãí°Õ
.\"O The
.\"O .I msgp
.\"O argument is declared as \fIstruct msgbuf *\fP with
.\"O libc4, libc5, glibc 2.0, glibc 2.1.
.\"O It is declared as \fIvoid *\fP
.\"O with glibc 2.2 and later, as required by SUSv2 and SUSv3.
.I msgp
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\fIstruct msgbuf *\fP ¤ÈÀë¸À¤µ¤ì¤Æ¤¤¤ë¡£glibc 2.2 °Ê¹ß¤Ç¤Ï¡¢
SUSv2 ¤È SUSv3 ¤ÎÍ×µáÄ̤ꡢ\fIvoid *\fP ¤ÈÀë¸À¤µ¤ì¤Æ¤¤¤ë¡£

.\"O The following limits on message queue resources affect the
.\"O .BR msgsnd ()
.\"O call:
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.B msgsnd
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.B MSGMAX
.\"O Maximum size for a message text: 8192 bytes
.\"O (on Linux, this limit can be read and modified via
.\"O .IR /proc/sys/kernel/msgmax ).
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.I /proc/sys/kernel/msgmax
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.B MSGMNB
.\"O Default maximum size in bytes of a message queue: 16384 bytes
.\"O (on Linux, this limit can be read and modified via
.\"O .IR /proc/sys/kernel/msgmnb ).
.\"O The superuser can increase the size of a message queue beyond
.\"O .B MSGMNB
.\"O by a
.\"O .BR msgctl (2)
.\"O system call.
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.BR msgctl (2)
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.B MSGMNB
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.\"O The implementation has no intrinsic limits for the system wide maximum
.\"O number of message headers
.\"O .RB ( MSGTQL )
.\"O and for the system wide maximum size in bytes of the message pool
.\"O .RB ( MSGPOOL ).
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.RB ( MSGTQL )
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.RB ( MSGPOOL )
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.\"O .SH "SEE ALSO"
.SH ´ØÏ¢¹àÌÜ
.BR msgctl (2),
.BR msgget (2),
.BR capabilities (7),
.BR mq_overview (7),
.BR svipc (7)