132 lines
5.2 KiB
HTML
132 lines
5.2 KiB
HTML
<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN">
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<link type="text/css" rel="stylesheet" href="style.css"><!-- Generated by The Open Group's rhtm tool v1.2.1 -->
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<!-- Copyright (c) 2001 The Open Group, All Rights Reserved -->
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<title><semaphore.h></title>
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</head>
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<body bgcolor="white">
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<script type="text/javascript" language="JavaScript" src="../jscript/codes.js">
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<basefont size="3"> <a name="<semaphore.h>"></a> <a name="tag_13_41"></a><!-- <semaphore.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_41_01"></a>NAME</h4>
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<blockquote>semaphore.h - semaphores (<b>REALTIME</b>)</blockquote>
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<h4><a name="tag_13_41_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('SEM')">SEM</a>]</sup> <img src="../images/opt-start.gif" alt=
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"[Option Start]" border="0"> #include <semaphore.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_41_03"></a>DESCRIPTION</h4>
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<blockquote>
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<p>The <i><semaphore.h></i> header shall define the <b>sem_t</b> type, used in performing semaphore operations. The semaphore
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may be implemented using a file descriptor, in which case applications are able to open up at least a total of {OPEN_MAX} files and
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semaphores. The symbol SEM_FAILED shall be defined (see <a href="../functions/sem_open.html"><i>sem_open</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 sem_close(sem_t *);
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int sem_destroy(sem_t *);
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int sem_getvalue(sem_t *restrict, int *restrict);
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int sem_init(sem_t *, int, unsigned);
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sem_t *sem_open(const char *, int, ...);
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int sem_post(sem_t *);
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<sup>[<a href="javascript:open_code('TMO')">TMO</a>]</sup><img src="../images/opt-start.gif" alt="[Option Start]" border="0">
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int sem_timedwait(sem_t *restrict, const struct timespec *restrict);
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<img src="../images/opt-end.gif" alt="[Option End]" border="0">
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int sem_trywait(sem_t *);
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int sem_unlink(const char *);
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int sem_wait(sem_t *);
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</tt>
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</pre>
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<p>Inclusion of the <i><semaphore.h></i> header may make visible symbols defined in the headers <a href=
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"../basedefs/fcntl.h.html"><i><fcntl.h></i></a> and <a href=
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"../basedefs/sys/types.h.html"><i><sys/types.h></i></a>.</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_41_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_41_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_41_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_41_07"></a>SEE ALSO</h4>
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<blockquote>
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<p><a href="fcntl.h.html"><i><fcntl.h></i></a> , <a href="sys/types.h.html"><i><sys/types.h></i></a> , the System
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Interfaces volume of IEEE Std 1003.1-2001, <a href="../functions/sem_destroy.html"><i>sem_destroy</i>()</a>, <a href=
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"../functions/sem_getvalue.html"><i>sem_getvalue</i>()</a>, <a href="../functions/sem_init.html"><i>sem_init</i>()</a>, <a href=
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"../functions/sem_open.html"><i>sem_open</i>()</a>, <a href="../functions/sem_post.html"><i>sem_post</i>()</a>, <a href=
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"../functions/sem_timedwait.html"><i>sem_timedwait</i>()</a>, <a href="../functions/sem_trywait.html"><i>sem_trywait</i>()</a>, <a
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href="../functions/sem_unlink.html"><i>sem_unlink</i>()</a>, <a href="../functions/sem_wait.html"><i>sem_wait</i>()</a></p>
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</blockquote>
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<h4><a name="tag_13_41_08"></a>CHANGE HISTORY</h4>
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<blockquote>
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<p>First released in Issue 5. Included for alignment with the POSIX Realtime Extension.</p>
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</blockquote>
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<h4><a name="tag_13_41_09"></a>Issue 6</h4>
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<blockquote>
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<p>The <i><semaphore.h></i> header is marked as part of the Semaphores option.</p>
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<p>The Open Group Corrigendum U021/3 is applied, adding a description of SEM_FAILED.</p>
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<p>The <a href="../functions/sem_timedwait.html"><i>sem_timedwait</i>()</a> function is added for alignment with
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IEEE Std 1003.1d-1999.</p>
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<p>The <b>restrict</b> keyword is added to the prototypes for <a href="../functions/sem_getvalue.html"><i>sem_getvalue</i>()</a>
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and <a href="../functions/sem_timedwait.html"><i>sem_timedwait</i>()</a>.</p>
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</blockquote>
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<div class="box"><em>End of informative text.</em></div>
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