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<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN"><html><head><meta name="generator" content="HTML Tidy, see www.w3.org"><meta http-equiv="Content-Type" content="text/html; charset=iso-8859-1"><link type="text/css" rel="stylesheet" href="style.css"><!-- Generated by The Open Group's rhtm tool v1.2.1 --><!-- Copyright (c) 2001-2003 The Open Group, All Rights Reserved --><title><sys/msg.h></title></head><body bgcolor="white"><script type="text/javascript" language="JavaScript" src="../../jscript/dotcode.js"></script><basefont size="3"> <a name="<sys/msg.h>"></a> <a name="tag_13_56"></a><!-- <sys/msg.h> --> <!--header start--><center><font size="2">The Open Group Base Specifications Issue 6<br>IEEE Std 1003.1, 2003 Edition<br>Copyright © 2001-2003 The IEEE and The Open Group, All Rights reserved.</font></center><!--header end--><hr size="2" noshade><h4><a name="tag_13_56_01"></a>NAME</h4><blockquote>sys/msg.h - XSI message queue structures</blockquote><h4><a name="tag_13_56_02"></a>SYNOPSIS</h4><blockquote class="synopsis"><div class="box"><tt><sup>[<a href="javascript:open_code('XSI')">XSI</a>]</sup> <img src="../../images/opt-start.gif" alt="[Option Start]" border="0"> #include <sys/msg.h> <img src="../../images/opt-end.gif" alt="[Option End]" border="0"></tt></div></blockquote><h4><a name="tag_13_56_03"></a>DESCRIPTION</h4><blockquote><p>The <i><sys/msg.h></i> header shall define the following data types through <b>typedef</b>:</p><dl compact><dt><b>msgqnum_t</b></dt><dd>Used for the number of messages in the message queue.</dd><dt><b>msglen_t</b></dt><dd>Used for the number of bytes allowed in a message queue.</dd></dl><p>These types shall be unsigned integer types that are able to store values at least as large as a type <b>unsigned short</b>.</p><p>The <i><sys/msg.h></i> header shall define the following constant as a message operation flag:</p><dl compact><dt>MSG_NOERROR</dt><dd>No error if big message.</dd></dl><p>The <b>msqid_ds</b> structure shall contain the following members:</p><pre><tt>struct ipc_perm msg_perm </tt> Operation permission structure. <tt>msgqnum_t msg_qnum </tt> Number of messages currently on queue. <tt>msglen_t msg_qbytes</tt> Maximum number of bytes allowed on queue. <tt>pid_t msg_lspid </tt> Process ID of last <i>msgsnd</i> (). <tt>pid_t msg_lrpid </tt> Process ID of last <i>msgrcv</i> (). <tt>time_t msg_stime </tt> Time of last <i>msgsnd</i> (). <tt>time_t msg_rtime </tt> Time of last <i>msgrcv</i> (). <tt>time_t msg_ctime </tt> Time of last change. <tt></tt></pre><p>The <b>pid_t</b>, <b>time_t</b>, <b>key_t</b>, <b>size_t</b>, and <b>ssize_t</b> types shall be defined as described in <a href="../sys/types.h.html#tag_13_67"><i><sys/types.h></i></a> .</p><p>The following shall be declared as functions and may also be defined as macros. Function prototypes shall be provided.</p><pre><tt>int msgctl(int, int, struct msqid_ds *);int msgget(key_t, int);ssize_t msgrcv(int, void *, size_t, long, int);int msgsnd(int, const void *, size_t, int);</tt></pre><p>In addition, all of the symbols from <a href="../../basedefs/sys/ipc.h.html"><i><sys/ipc.h></i></a> shall be defined whenthis header is included.</p></blockquote><hr><div class="box"><em>The following sections are informative.</em></div><h4><a name="tag_13_56_04"></a>APPLICATION USAGE</h4><blockquote><p>None.</p></blockquote><h4><a name="tag_13_56_05"></a>RATIONALE</h4><blockquote><p>None.</p></blockquote><h4><a name="tag_13_56_06"></a>FUTURE DIRECTIONS</h4><blockquote><p>None.</p></blockquote><h4><a name="tag_13_56_07"></a>SEE ALSO</h4><blockquote><p><a href="../sys/ipc.h.html#tag_13_54"><i><sys/ipc.h></i></a> , <a href="../sys/types.h.html#tag_13_67"><i><sys/types.h></i></a> , <a href="../../functions/msgctl.html"><i>msgctl</i>()</a>, <ahref="../../functions/msgget.html"><i>msgget</i>()</a>, <a href="../../functions/msgrcv.html"><i>msgrcv</i>()</a>, <a href="../../functions/msgsnd.html"><i>msgsnd</i>()</a></p></blockquote><h4><a name="tag_13_56_08"></a>CHANGE HISTORY</h4><blockquote><p>First released in Issue 2. Derived from System V Release 2.0.</p></blockquote><div class="box"><em>End of informative text.</em></div><hr><hr size="2" noshade><center><font size="2"><!--footer start-->UNIX ® is a registered Trademark of The Open Group.<br>POSIX ® is a registered Trademark of The IEEE.<br>[ <a href="../../mindex.html">Main Index</a> | <a href="../../basedefs/contents.html">XBD</a> | <a href="../../utilities/contents.html">XCU</a> | <a href="../../functions/contents.html">XSH</a> | <a href="../../xrat/contents.html">XRAT</a> ]</font></center><!--footer end--><hr size="2" noshade></body></html>⌨️ 快捷键说明
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