138 lines
5.2 KiB
HTML
138 lines
5.2 KiB
HTML
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<!-- Copyright (c) 2001 The Open Group, All Rights Reserved -->
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<title>sem_close</title>
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<basefont size="3"> <a name="sem_close"></a> <a name="tag_03_628"></a><!-- sem_close -->
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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_03_628_01"></a>NAME</h4>
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<blockquote>sem_close - close a named semaphore (<b>REALTIME</b>)</blockquote>
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<h4><a name="tag_03_628_02"></a>SYNOPSIS</h4>
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<blockquote class="synopsis">
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<div class="box"><code><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 <<a href="../basedefs/semaphore.h.html">semaphore.h</a>><br>
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<br>
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int sem_close(sem_t *</tt><i>sem</i><tt>); <img src="../images/opt-end.gif" alt="[Option End]" border="0"></tt></code></div>
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<tt><br>
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</tt></blockquote>
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<h4><a name="tag_03_628_03"></a>DESCRIPTION</h4>
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<blockquote>
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<p>The <i>sem_close</i>() function shall indicate that the calling process is finished using the named semaphore indicated by
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<i>sem</i>. The effects of calling <i>sem_close</i>() for an unnamed semaphore (one created by <a href=
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"../functions/sem_init.html"><i>sem_init</i>()</a>) are undefined. The <i>sem_close</i>() function shall deallocate (that is, make
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available for reuse by a subsequent <a href="../functions/sem_open.html"><i>sem_open</i>()</a> by this process) any system
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resources allocated by the system for use by this process for this semaphore. The effect of subsequent use of the semaphore
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indicated by <i>sem</i> by this process is undefined. If the semaphore has not been removed with a successful call to <a href=
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"../functions/sem_unlink.html"><i>sem_unlink</i>()</a>, then <i>sem_close</i>() has no effect on the state of the semaphore. If the
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<a href="../functions/sem_unlink.html"><i>sem_unlink</i>()</a> function has been successfully invoked for <i>name</i> after the
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most recent call to <a href="../functions/sem_open.html"><i>sem_open</i>()</a> with O_CREAT for this semaphore, then when all
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processes that have opened the semaphore close it, the semaphore is no longer accessible.</p>
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</blockquote>
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<h4><a name="tag_03_628_04"></a>RETURN VALUE</h4>
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<blockquote>
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<p>Upon successful completion, a value of zero shall be returned. Otherwise, a value of -1 shall be returned and <i>errno</i> set
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to indicate the error.</p>
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</blockquote>
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<h4><a name="tag_03_628_05"></a>ERRORS</h4>
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<blockquote>
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<p>The <i>sem_close</i>() function shall fail if:</p>
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<dl compact>
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<dt>[EINVAL]</dt>
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<dd>The <i>sem</i> argument is not a valid semaphore descriptor.</dd>
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</dl>
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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_03_628_06"></a>EXAMPLES</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_03_628_07"></a>APPLICATION USAGE</h4>
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<blockquote>
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<p>The <i>sem_close</i>() function is part of the Semaphores option and need not be available on all implementations.</p>
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</blockquote>
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<h4><a name="tag_03_628_08"></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_03_628_09"></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_03_628_10"></a>SEE ALSO</h4>
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<blockquote>
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<p><a href="semctl.html"><i>semctl</i>()</a> , <a href="semget.html"><i>semget</i>()</a> , <a href="semop.html"><i>semop</i>()</a>
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, <a href="sem_init.html"><i>sem_init</i>()</a> , <a href="sem_open.html"><i>sem_open</i>()</a> , <a href=
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"sem_unlink.html"><i>sem_unlink</i>()</a> , the Base Definitions volume of IEEE Std 1003.1-2001, <a href=
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"../basedefs/semaphore.h.html"><i><semaphore.h></i></a></p>
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</blockquote>
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<h4><a name="tag_03_628_11"></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_03_628_12"></a>Issue 6</h4>
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<blockquote>
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<p>The <i>sem_close</i>() function is marked as part of the Semaphores option.</p>
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<p>The [ENOSYS] error condition has been removed as stubs need not be provided if an implementation does not support the Semaphores
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option.</p>
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</blockquote>
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<div class="box"><em>End of informative text.</em></div>
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