210 lines
7.3 KiB
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210 lines
7.3 KiB
HTML
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<title>mprotect</title>
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<basefont size="3"> <a name="mprotect"></a> <a name="tag_03_381"></a><!-- mprotect -->
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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_381_01"></a>NAME</h4>
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<blockquote>mprotect - set protection of memory mapping</blockquote>
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<h4><a name="tag_03_381_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('MPR')">MPR</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 mprotect(void *</tt><i>addr</i><tt>, size_t</tt> <i>len</i><tt>, int</tt> <i>prot</i><tt>); <img src="../images/opt-end.gif"
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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_381_03"></a>DESCRIPTION</h4>
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<blockquote>
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<p>The <i>mprotect</i>() function shall change the access protections to be that specified by <i>prot</i> for those whole pages
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containing any part of the address space of the process starting at address <i>addr</i> and continuing for <i>len</i> bytes. The
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parameter <i>prot</i> determines whether read, write, execute, or some combination of accesses are permitted to the data being
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mapped. The <i>prot</i> argument should be either PROT_NONE or the bitwise-inclusive OR of one or more of PROT_READ, PROT_WRITE,
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and PROT_EXEC.</p>
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<p>If an implementation cannot support the combination of access types specified by <i>prot</i>, the call to <i>mprotect</i>()
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shall fail.</p>
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<p>An implementation may permit accesses other than those specified by <i>prot</i>; however, no implementation shall permit a write
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to succeed where PROT_WRITE has not been set or shall permit any access where PROT_NONE alone has been set. Implementations shall
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support at least the following values of <i>prot</i>: PROT_NONE, PROT_READ, PROT_WRITE, and the bitwise-inclusive OR of PROT_READ
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and PROT_WRITE. If PROT_WRITE is specified, the application shall ensure that it has opened the mapped objects in the specified
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address range with write permission, unless MAP_PRIVATE was specified in the original mapping, regardless of whether the file
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descriptors used to map the objects have since been closed.</p>
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<p>The implementation shall require that <i>addr</i> be a multiple of the page size as returned by <a href=
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"../functions/sysconf.html"><i>sysconf</i>()</a>.</p>
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<p>The behavior of this function is unspecified if the mapping was not established by a call to <a href=
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"../functions/mmap.html"><i>mmap</i>()</a>.</p>
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<p>When <i>mprotect</i>() fails for reasons other than [EINVAL], the protections on some of the pages in the range
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[<i>addr</i>,<i>addr</i>+<i>len</i>) may have been changed.</p>
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</blockquote>
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<h4><a name="tag_03_381_04"></a>RETURN VALUE</h4>
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<blockquote>
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<p>Upon successful completion, <i>mprotect</i>() shall return 0; otherwise, it shall return -1 and set <i>errno</i> to indicate the
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error.</p>
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</blockquote>
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<h4><a name="tag_03_381_05"></a>ERRORS</h4>
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<blockquote>
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<p>The <i>mprotect</i>() function shall fail if:</p>
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<dl compact>
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<dt>[EACCES]</dt>
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<dd>The <i>prot</i> argument specifies a protection that violates the access permission the process has to the underlying memory
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object.</dd>
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<dt>[EAGAIN]</dt>
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<dd>The <i>prot</i> argument specifies PROT_WRITE over a MAP_PRIVATE mapping and there are insufficient memory resources to reserve
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for locking the private page.</dd>
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<dt>[EINVAL]</dt>
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<dd>The <i>addr</i> argument is not a multiple of the page size as returned by <a href=
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"../functions/sysconf.html"><i>sysconf</i>()</a>.</dd>
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<dt>[ENOMEM]</dt>
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<dd>Addresses in the range [<i>addr</i>,<i>addr</i>+<i>len</i>) are invalid for the address space of a process, or specify one or
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more pages which are not mapped.</dd>
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<dt>[ENOMEM]</dt>
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<dd>The <i>prot</i> argument specifies PROT_WRITE on a MAP_PRIVATE mapping, and it would require more space than the system is able
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to supply for locking the private pages, if required.</dd>
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<dt>[ENOTSUP]</dt>
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<dd>The implementation does not support the combination of accesses requested in the <i>prot</i> argument.</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_381_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_381_07"></a>APPLICATION USAGE</h4>
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<blockquote>
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<p>The [EINVAL] error above is marked EX because it is defined as an optional error in the POSIX Realtime Extension.</p>
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</blockquote>
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<h4><a name="tag_03_381_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_381_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_381_10"></a>SEE ALSO</h4>
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<blockquote>
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<p><a href="mmap.html"><i>mmap</i>()</a> , <a href="sysconf.html"><i>sysconf</i>()</a> , the Base Definitions volume of
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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_381_11"></a>CHANGE HISTORY</h4>
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<blockquote>
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<p>First released in Issue 4, Version 2.</p>
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</blockquote>
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<h4><a name="tag_03_381_12"></a>Issue 5</h4>
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<blockquote>
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<p>Moved from X/OPEN UNIX extension to BASE.</p>
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<p>Aligned with <i>mprotect</i>() in the POSIX Realtime Extension as follows:</p>
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<ul>
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<li>
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<p>The DESCRIPTION is largely reworded.</p>
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</li>
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<li>
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<p>[ENOTSUP] and a second form of [ENOMEM] are added as mandatory error conditions.</p>
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</li>
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<li>
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<p>[EAGAIN] is moved from the optional to the mandatory error conditions.</p>
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</li>
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</ul>
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</blockquote>
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<h4><a name="tag_03_381_13"></a>Issue 6</h4>
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<blockquote>
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<p>The <i>mprotect</i>() function is marked as part of the Memory Protection option.</p>
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<p>The following new requirements on POSIX implementations derive from alignment with the Single UNIX Specification:</p>
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<ul>
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<li>
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<p>The DESCRIPTION is updated to state that implementations require <i>addr</i> to be a multiple of the page size as returned by <a
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href="../functions/sysconf.html"><i>sysconf</i>()</a>.</p>
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</li>
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<li>
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<p>The [EINVAL] error condition is added.</p>
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</li>
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</ul>
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<p>The DESCRIPTION is updated to avoid use of the term "must" for application requirements.</p>
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</blockquote>
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<div class="box"><em>End of informative text.</em></div>
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<hr>
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<center><font size="2"><!--footer start-->
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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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