📄 sem.h.html
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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/sem.h></title></head><body bgcolor="white"><script type="text/javascript" language="JavaScript" src="../../jscript/dotcode.js"></script><basefont size="3"> <a name="<sys/sem.h>"></a> <a name="tag_13_59"></a><!-- <sys/sem.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_59_01"></a>NAME</h4><blockquote>sys/sem.h - XSI semaphore facility</blockquote><h4><a name="tag_13_59_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/sem.h> <img src="../../images/opt-end.gif" alt="[Option End]" border="0"></tt></div></blockquote><h4><a name="tag_13_59_03"></a>DESCRIPTION</h4><blockquote><p>The <i><sys/sem.h></i> header shall define the following constants and structures.</p><p>Semaphore operation flags:</p><dl compact><dt>SEM_UNDO</dt><dd>Set up adjust on exit entry.</dd></dl><p>Command definitions for the <a href="../../functions/semctl.html"><i>semctl</i>()</a> function shall be provided as follows:</p><dl compact><dt>GETNCNT</dt><dd>Get <i>semncnt</i>.</dd><dt>GETPID</dt><dd>Get <i>sempid</i>.</dd><dt>GETVAL</dt><dd>Get <i>semval</i>.</dd><dt>GETALL</dt><dd>Get all cases of <i>semval</i>.</dd><dt>GETZCNT</dt><dd>Get <i>semzcnt</i>.</dd><dt>SETVAL</dt><dd>Set <i>semval</i>.</dd><dt>SETALL</dt><dd>Set all cases of <i>semval</i>.</dd></dl><p>The <b>semid_ds</b> structure shall contain the following members:</p><pre><tt>struct ipc_perm sem_perm </tt> Operation permission structure. <tt>unsigned short sem_nsems</tt> Number of semaphores in set. <tt>time_t sem_otime</tt> Last <i>semop</i> () time. <tt>time_t sem_ctime</tt> Last time changed by <i>semctl</i> (). <tt></tt></pre><p>The <b>pid_t</b>, <b>time_t</b>, <b>key_t</b>, and <b>size_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>A semaphore shall be represented by an anonymous structure containing the following members:</p><pre><tt>unsigned short semval </tt> Semaphore value. <tt>pid_t sempid </tt> Process ID of last operation. <tt>unsigned short semncnt </tt> Number of processes waiting for <i>semval</i> <tt> </tt> to become greater than current value. <tt>unsigned short semzcnt </tt> Number of processes waiting for <i>semval</i> <tt> </tt> to become 0. <tt></tt></pre><p>The <b>sembuf</b> structure shall contain the following members:</p><pre><tt>unsigned short sem_num </tt> Semaphore number. <tt>short sem_op </tt> Semaphore operation. <tt>short sem_flg </tt> Operation flags. <tt></tt></pre><p>The following shall be declared as functions and may also be defined as macros. Function prototypes shall be provided.</p><pre><tt>int semctl(int, int, int, ...);int semget(key_t, int, int);int semop(int, struct sembuf *, size_t);</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_59_04"></a>APPLICATION USAGE</h4><blockquote><p>None.</p></blockquote><h4><a name="tag_13_59_05"></a>RATIONALE</h4><blockquote><p>None.</p></blockquote><h4><a name="tag_13_59_06"></a>FUTURE DIRECTIONS</h4><blockquote><p>None.</p></blockquote><h4><a name="tag_13_59_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/semctl.html"><i>semctl</i>()</a>, <ahref="../../functions/semget.html"><i>semget</i>()</a>, <a href="../../functions/semop.html"><i>semop</i>()</a></p></blockquote><h4><a name="tag_13_59_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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