146 lines
4.8 KiB
HTML
146 lines
4.8 KiB
HTML
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<!-- Copyright (c) 2001 The Open Group, All Rights Reserved -->
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<title><sys/msg.h></title>
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<basefont size="3"> <a name="<sys/msg.h>"></a> <a name="tag_13_56"></a><!-- <sys/msg.h> -->
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<!--header start-->
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<center><font size="2">The Open Group Base Specifications Issue 6<br>
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IEEE Std 1003.1-2001<br>
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Copyright © 2001 The IEEE and The Open Group, All Rights reserved.</font></center>
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<!--header end-->
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<hr size="2" noshade>
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<h4><a name="tag_13_56_01"></a>NAME</h4>
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<blockquote>sys/msg.h - XSI message queue structures</blockquote>
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<h4><a name="tag_13_56_02"></a>SYNOPSIS</h4>
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<blockquote class="synopsis">
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<div class="box"><tt><sup>[<a href="javascript:open_code('XSI')">XSI</a>]</sup> <img src="../../images/opt-start.gif" alt=
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"[Option Start]" border="0"> #include <sys/msg.h> <img src="../../images/opt-end.gif" alt="[Option End]" border=
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"0"></tt></div>
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</blockquote>
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<h4><a name="tag_13_56_03"></a>DESCRIPTION</h4>
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<blockquote>
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<p>The <i><sys/msg.h></i> header shall define the following data types through <b>typedef</b>:</p>
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<dl compact>
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<dt><b>msgqnum_t</b></dt>
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<dd>Used for the number of messages in the message queue.</dd>
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<dt><b>msglen_t</b></dt>
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<dd>Used for the number of bytes allowed in a message queue.</dd>
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</dl>
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<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>
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<p>The <i><sys/msg.h></i> header shall define the following constant as a message operation flag:</p>
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<dl compact>
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<dt>MSG_NOERROR</dt>
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<dd>No error if big message.</dd>
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</dl>
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<p>The <b>msqid_ds</b> structure shall contain the following members:</p>
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<pre>
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<tt>struct ipc_perm msg_perm </tt> Operation permission structure. <tt>
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msgqnum_t msg_qnum </tt> Number of messages currently on queue. <tt>
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msglen_t msg_qbytes</tt> Maximum number of bytes allowed on queue. <tt>
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pid_t msg_lspid </tt> Process ID of last <i>msgsnd</i>
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(). <tt>
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pid_t msg_lrpid </tt> Process ID of last <i>msgrcv</i>
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(). <tt>
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time_t msg_stime </tt> Time of last <i>msgsnd</i>
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(). <tt>
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time_t msg_rtime </tt> Time of last <i>msgrcv</i>
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(). <tt>
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time_t msg_ctime </tt> Time of last change. <tt>
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</tt>
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</pre>
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<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=
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"../sys/types.h.html#tag_13_67"><i><sys/types.h></i></a> .</p>
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<p>The following shall be declared as functions and may also be defined as macros. Function prototypes shall be provided.</p>
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<pre>
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<tt>int msgctl(int, int, struct msqid_ds *);
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int msgget(key_t, int);
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ssize_t msgrcv(int, void *, size_t, long, int);
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int msgsnd(int, const void *, size_t, int);
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</tt>
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</pre>
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<p>In addition, all of the symbols from <a href="../../basedefs/sys/ipc.h.html"><i><sys/ipc.h></i></a> shall be defined when
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this header is included.</p>
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</blockquote>
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<hr>
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<div class="box"><em>The following sections are informative.</em></div>
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<h4><a name="tag_13_56_04"></a>APPLICATION USAGE</h4>
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<blockquote>
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<p>None.</p>
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</blockquote>
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<h4><a name="tag_13_56_05"></a>RATIONALE</h4>
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<blockquote>
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<p>None.</p>
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</blockquote>
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<h4><a name="tag_13_56_06"></a>FUTURE DIRECTIONS</h4>
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<blockquote>
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<p>None.</p>
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</blockquote>
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<h4><a name="tag_13_56_07"></a>SEE ALSO</h4>
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<blockquote>
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<p><a href="../sys/ipc.h.html#tag_13_54"><i><sys/ipc.h></i></a> , <a href=
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"../sys/types.h.html#tag_13_67"><i><sys/types.h></i></a> , <a href="../../functions/msgctl.html"><i>msgctl</i>()</a>, <a
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href="../../functions/msgget.html"><i>msgget</i>()</a>, <a href="../../functions/msgrcv.html"><i>msgrcv</i>()</a>, <a href=
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"../../functions/msgsnd.html"><i>msgsnd</i>()</a></p>
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</blockquote>
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<h4><a name="tag_13_56_08"></a>CHANGE HISTORY</h4>
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<blockquote>
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<p>First released in Issue 2. Derived from System V Release 2.0.</p>
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</blockquote>
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<div class="box"><em>End of informative text.</em></div>
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UNIX ® is a registered Trademark of The Open Group.<br>
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POSIX ® is a registered Trademark of The IEEE.<br>
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