180 lines
6.7 KiB
HTML
180 lines
6.7 KiB
HTML
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<title>mlock</title>
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<basefont size="3"> <a name="mlock"></a> <a name="tag_03_377"></a><!-- mlock -->
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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_377_01"></a>NAME</h4>
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<blockquote>mlock, munlock - lock or unlock a range of process address space (<b>REALTIME</b>)</blockquote>
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<h4><a name="tag_03_377_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('MR')">MR</a>]</sup> <img src="../images/opt-start.gif" alt=
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"[Option Start]" border="0"> #include <<a href="../basedefs/sys/mman.h.html">sys/mman.h</a>><br>
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<br>
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int mlock(const void *</tt><i>addr</i><tt>, size_t</tt> <i>len</i><tt>);<br>
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int munlock(const void *</tt><i>addr</i><tt>, size_t</tt> <i>len</i><tt>); <img src="../images/opt-end.gif" alt="[Option End]"
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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_377_03"></a>DESCRIPTION</h4>
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<blockquote>
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<p>The <i>mlock</i>() function shall cause those whole pages containing any part of the address space of the process starting at
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address <i>addr</i> and continuing for <i>len</i> bytes to be memory-resident until unlocked or until the process exits or <i><a
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href="../functions/exec.html">exec</a></i>s another process image. The implementation may require that <i>addr</i> be a multiple of
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{PAGESIZE}.</p>
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<p>The <i>munlock</i>() function shall unlock those whole pages containing any part of the address space of the process starting at
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address <i>addr</i> and continuing for <i>len</i> bytes, regardless of how many times <i>mlock</i>() has been called by the process
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for any of the pages in the specified range. The implementation may require that <i>addr</i> be a multiple of {PAGESIZE}.</p>
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<p>If any of the pages in the range specified to a call to <i>munlock</i>() are also mapped into the address spaces of other
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processes, any locks established on those pages by another process are unaffected by the call of this process to <i>munlock</i>().
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If any of the pages in the range specified by a call to <i>munlock</i>() are also mapped into other portions of the address space
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of the calling process outside the range specified, any locks established on those pages via the other mappings are also unaffected
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by this call.</p>
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<p>Upon successful return from <i>mlock</i>(), pages in the specified range shall be locked and memory-resident. Upon successful
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return from <i>munlock</i>(), pages in the specified range shall be unlocked with respect to the address space of the process.
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Memory residency of unlocked pages is unspecified.</p>
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<p>The appropriate privilege is required to lock process memory with <i>mlock</i>().</p>
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</blockquote>
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<h4><a name="tag_03_377_04"></a>RETURN VALUE</h4>
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<blockquote>
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<p>Upon successful completion, the <i>mlock</i>() and <i>munlock</i>() functions shall return a value of zero. Otherwise, no change
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is made to any locks in the address space of the process, and the function shall return a value of -1 and set <i>errno</i> to
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indicate the error.</p>
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</blockquote>
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<h4><a name="tag_03_377_05"></a>ERRORS</h4>
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<blockquote>
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<p>The <i>mlock</i>() and <i>munlock</i>() functions shall fail if:</p>
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<dl compact>
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<dt>[ENOMEM]</dt>
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<dd>Some or all of the address range specified by the <i>addr</i> and <i>len</i> arguments does not correspond to valid mapped
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pages in the address space of the process.</dd>
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</dl>
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<p>The <i>mlock</i>() function shall fail if:</p>
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<dl compact>
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<dt>[EAGAIN]</dt>
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<dd>Some or all of the memory identified by the operation could not be locked when the call was made.</dd>
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</dl>
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<p>The <i>mlock</i>() and <i>munlock</i>() functions may fail if:</p>
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<dl compact>
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<dt>[EINVAL]</dt>
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<dd>The <i>addr</i> argument is not a multiple of {PAGESIZE}.</dd>
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</dl>
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<p>The <i>mlock</i>() function may fail if:</p>
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<dl compact>
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<dt>[ENOMEM]</dt>
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<dd>Locking the pages mapped by the specified range would exceed an implementation-defined limit on the amount of memory that the
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process may lock.</dd>
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<dt>[EPERM]</dt>
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<dd>The calling process does not have the appropriate privilege to perform the requested operation.</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_377_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_377_07"></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_03_377_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_377_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_377_10"></a>SEE ALSO</h4>
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<blockquote>
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<p><a href="exec.html"><i><a href="../functions/exec.html">exec</a></i>()</a> , <a href="exit.html"><i>exit</i>()</a> , <a href=
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"fork.html"><i>fork</i>()</a> , <a href="mlockall.html"><i>mlockall</i>()</a> , <a href="munmap.html"><i>munmap</i>()</a> , the
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Base Definitions volume of IEEE Std 1003.1-2001, <a href="../basedefs/sys/mman.h.html"><i><sys/mman.h></i></a></p>
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</blockquote>
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<h4><a name="tag_03_377_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_377_12"></a>Issue 6</h4>
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<blockquote>
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<p>The <i>mlock</i>() and <i>munlock</i>() functions are marked as part of the Range Memory Locking 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 Range
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Memory Locking 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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