156 lines
6.2 KiB
HTML
156 lines
6.2 KiB
HTML
<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN">
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<meta name="generator" content="HTML Tidy, see www.w3.org">
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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>dlclose</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="dlclose"></a> <a name="tag_03_109"></a><!-- dlclose -->
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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_109_01"></a>NAME</h4>
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<blockquote>dlclose - close a dlopen object</blockquote>
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<h4><a name="tag_03_109_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('XSI')">XSI</a>]</sup> <img src="../images/opt-start.gif" alt=
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"[Option Start]" border="0"> #include <<a href="../basedefs/dlfcn.h.html">dlfcn.h</a>><br>
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<br>
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int dlclose(void *</tt><i>handle</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_109_03"></a>DESCRIPTION</h4>
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<blockquote>
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<p>The <i>dlclose</i>() function shall inform the system that the object referenced by a <i>handle</i> returned from a previous <a
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href="../functions/dlopen.html"><i>dlopen</i>()</a> invocation is no longer needed by the application.</p>
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<p>The use of <i>dlclose</i>() reflects a statement of intent on the part of the process, but does not create any requirement upon
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the implementation, such as removal of the code or symbols referenced by <i>handle</i>. Once an object has been closed using
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<i>dlclose</i>() an application should assume that its symbols are no longer available to <a href=
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"../functions/dlsym.html"><i>dlsym</i>()</a>. All objects loaded automatically as a result of invoking <a href=
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"../functions/dlopen.html"><i>dlopen</i>()</a> on the referenced object shall also be closed if this is the last reference to
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it.</p>
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<p>Although a <i>dlclose</i>() operation is not required to remove structures from an address space, neither is an implementation
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prohibited from doing so. The only restriction on such a removal is that no object shall be removed to which references have been
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relocated, until or unless all such references are removed. For instance, an object that had been loaded with a <a href=
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"../functions/dlopen.html"><i>dlopen</i>()</a> operation specifying the RTLD_GLOBAL flag might provide a target for dynamic
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relocations performed in the processing of other objects-in such environments, an application may assume that no relocation, once
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made, shall be undone or remade unless the object requiring the relocation has itself been removed.</p>
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</blockquote>
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<h4><a name="tag_03_109_04"></a>RETURN VALUE</h4>
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<blockquote>
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<p>If the referenced object was successfully closed, <i>dlclose</i>() shall return 0. If the object could not be closed, or if
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<i>handle</i> does not refer to an open object, <i>dlclose</i>() shall return a non-zero value. More detailed diagnostic
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information shall be available through <a href="../functions/dlerror.html"><i>dlerror</i>()</a>.</p>
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</blockquote>
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<h4><a name="tag_03_109_05"></a>ERRORS</h4>
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<blockquote>
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<p>No errors are defined.</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_03_109_06"></a>EXAMPLES</h4>
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<blockquote>
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<p>The following example illustrates use of <a href="../functions/dlopen.html"><i>dlopen</i>()</a> and <i>dlclose</i>():</p>
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<pre>
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<tt>...
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/* Open a dynamic library and then close it ... */
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<br>
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#include <dlfcn.h>
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void *mylib;
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int eret;
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<br>
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mylib = dlopen("mylib.so", RTLD_LOCAL | RTLD_LAZY);
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...
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eret = dlclose(mylib);
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...
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</tt>
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</pre>
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</blockquote>
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<h4><a name="tag_03_109_07"></a>APPLICATION USAGE</h4>
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<blockquote>
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<p>A conforming application should employ a <i>handle</i> returned from a <a href="../functions/dlopen.html"><i>dlopen</i>()</a>
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invocation only within a given scope bracketed by the <a href="../functions/dlopen.html"><i>dlopen</i>()</a> and <i>dlclose</i>()
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operations. Implementations are free to use reference counting or other techniques such that multiple calls to <a href=
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"../functions/dlopen.html"><i>dlopen</i>()</a> referencing the same object may return the same object for <i>handle</i>.
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Implementations are also free to reuse a <i>handle</i>. For these reasons, the value of a <i>handle</i> must be treated as an
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opaque object by the application, used only in calls to <a href="../functions/dlsym.html"><i>dlsym</i>()</a> and
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<i>dlclose</i>().</p>
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</blockquote>
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<h4><a name="tag_03_109_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_109_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_109_10"></a>SEE ALSO</h4>
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<blockquote>
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<p><a href="dlerror.html"><i>dlerror</i>()</a> , <a href="dlopen.html"><i>dlopen</i>()</a> , <a href=
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"dlsym.html"><i>dlsym</i>()</a> , the Base Definitions volume of IEEE Std 1003.1-2001, <a href=
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"../basedefs/dlfcn.h.html"><i><dlfcn.h></i></a></p>
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</blockquote>
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<h4><a name="tag_03_109_11"></a>CHANGE HISTORY</h4>
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<blockquote>
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<p>First released in Issue 5.</p>
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</blockquote>
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<h4><a name="tag_03_109_12"></a>Issue 6</h4>
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<blockquote>
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<p>The DESCRIPTION is updated to say that the referenced object is closed "if this is the last reference to it".</p>
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</blockquote>
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<div class="box"><em>End of informative text.</em></div>
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