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diff --git a/rubbos/app/httpd-2.0.64/docs/manual/developer/hooks.html.en b/rubbos/app/httpd-2.0.64/docs/manual/developer/hooks.html.en new file mode 100644 index 00000000..b89e9906 --- /dev/null +++ b/rubbos/app/httpd-2.0.64/docs/manual/developer/hooks.html.en @@ -0,0 +1,239 @@ +<?xml version="1.0" encoding="ISO-8859-1"?> +<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Strict//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-strict.dtd"> +<html xmlns="http://www.w3.org/1999/xhtml" lang="en" xml:lang="en"><head><!-- + XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX + This file is generated from xml source: DO NOT EDIT + XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX + --> +<title>Apache 2.0 Hook Functions - Apache HTTP Server</title> +<link href="../style/css/manual.css" rel="stylesheet" media="all" type="text/css" title="Main stylesheet" /> +<link href="../style/css/manual-loose-100pc.css" rel="alternate stylesheet" media="all" type="text/css" title="No Sidebar - Default font size" /> +<link href="../style/css/manual-print.css" rel="stylesheet" media="print" type="text/css" /> +<link href="../images/favicon.ico" rel="shortcut icon" /></head> +<body id="manual-page"><div id="page-header"> +<p class="menu"><a href="../mod/">Modules</a> | <a href="../mod/directives.html">Directives</a> | <a href="../faq/">FAQ</a> | <a href="../glossary.html">Glossary</a> | <a href="../sitemap.html">Sitemap</a></p> +<p class="apache">Apache HTTP Server Version 2.0</p> +<img alt="" src="../images/feather.gif" /></div> +<div class="up"><a href="./"><img title="<-" alt="<-" src="../images/left.gif" /></a></div> +<div id="path"> +<a href="http://www.apache.org/">Apache</a> > <a href="http://httpd.apache.org/">HTTP Server</a> > <a href="http://httpd.apache.org/docs/">Documentation</a> > <a href="../">Version 2.0</a> > <a href="./">Developer Documentation</a></div><div id="page-content"><div id="preamble"><h1>Apache 2.0 Hook Functions</h1> +<div class="toplang"> +<p><span>Available Languages: </span><a href="../en/developer/hooks.html" title="English"> en </a></p> +</div> + + <div class="warning"><h3>Warning</h3> + <p>This document is still in development and may be partially out of + date.</p> + </div> + + <p>In general, a hook function is one that Apache will call at + some point during the processing of a request. Modules can + provide functions that are called, and specify when they get + called in comparison to other modules.</p> +</div> +<div id="quickview"><ul id="toc"><li><img alt="" src="../images/down.gif" /> <a href="#create">Creating a hook function</a></li> +<li><img alt="" src="../images/down.gif" /> <a href="#hooking">Hooking the hook</a></li> +</ul></div> +<div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div> +<div class="section"> +<h2><a name="create" id="create">Creating a hook function</a></h2> + <p>In order to create a new hook, four things need to be + done:</p> + + <h3><a name="create-declare" id="create-declare">Declare the hook function</a></h3> + <p>Use the <code>AP_DECLARE_HOOK</code> macro, which needs to be given + the return type of the hook function, the name of the hook, and the + arguments. For example, if the hook returns an <code>int</code> and + takes a <code>request_rec *</code> and an <code>int</code> and is + called <code>do_something</code>, then declare it like this:</p> + <div class="example"><p><code> + AP_DECLARE_HOOK(int, do_something, (request_rec *r, int n)) + </code></p></div> + + <p>This should go in a header which modules will include if + they want to use the hook.</p> + + + <h3><a name="create-create" id="create-create">Create the hook structure</a></h3> + <p>Each source file that exports a hook has a private structure + which is used to record the module functions that use the hook. + This is declared as follows:</p> + + <div class="example"><p><code> + APR_HOOK_STRUCT(<br /> + <span class="indent"> + APR_HOOK_LINK(do_something)<br /> + ...<br /> + </span> + ) + </code></p></div> + + + <h3><a name="create-implement" id="create-implement">Implement the hook caller</a></h3> + <p>The source file that exports the hook has to implement a + function that will call the hook. There are currently three + possible ways to do this. In all cases, the calling function is + called <code>ap_run_<var>hookname</var>()</code>.</p> + + <h4>Void hooks</h4> + <p>If the return value of a hook is <code>void</code>, then all the + hooks are called, and the caller is implemented like this:</p> + + <div class="example"><p><code> + AP_IMPLEMENT_HOOK_VOID(do_something, (request_rec *r, int n), (r, n)) + </code></p></div> + + <p>The second and third arguments are the dummy argument + declaration and the dummy arguments as they will be used when + calling the hook. In other words, this macro expands to + something like this:</p> + + <div class="example"><p><code> + void ap_run_do_something(request_rec *r, int n)<br /> + {<br /> + <span class="indent"> + ...<br /> + do_something(r, n);<br /> + </span> + } + </code></p></div> + + + <h4>Hooks that return a value</h4> + <p>If the hook returns a value, then it can either be run until + the first hook that does something interesting, like so:</p> + + <div class="example"><p><code> + AP_IMPLEMENT_HOOK_RUN_FIRST(int, do_something, (request_rec *r, int n), (r, n), DECLINED) + </code></p></div> + + <p>The first hook that does <em>not</em> return <code>DECLINED</code> + stops the loop and its return value is returned from the hook + caller. Note that <code>DECLINED</code> is the tradition Apache + hook return meaning "I didn't do anything", but it can be + whatever suits you.</p> + + <p>Alternatively, all hooks can be run until an error occurs. + This boils down to permitting <em>two</em> return values, one of + which means "I did something, and it was OK" and the other + meaning "I did nothing". The first function that returns a + value other than one of those two stops the loop, and its + return is the return value. Declare these like so:</p> + + <div class="example"><p><code> + AP_IMPLEMENT_HOOK_RUN_ALL(int, do_something, (request_rec *r, int n), (r, n), OK, DECLINED) + </code></p></div> + + <p>Again, <code>OK</code> and <code>DECLINED</code> are the traditional + values. You can use what you want.</p> + + + + <h3><a name="create-call" id="create-call">Call the hook callers</a></h3> + <p>At appropriate moments in the code, call the hook caller, + like so:</p> + + <div class="example"><p><code> + int n, ret;<br /> + request_rec *r;<br /> + <br /> + ret=ap_run_do_something(r, n); + </code></p></div> + +</div><div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div> +<div class="section"> +<h2><a name="hooking" id="hooking">Hooking the hook</a></h2> + <p>A module that wants a hook to be called needs to do two + things.</p> + + <h3><a name="hooking-implement" id="hooking-implement">Implement the hook function</a></h3> + <p>Include the appropriate header, and define a static function + of the correct type:</p> + + <div class="example"><p><code> + static int my_something_doer(request_rec *r, int n)<br /> + {<br /> + <span class="indent"> + ...<br /> + return OK;<br /> + </span> + } + </code></p></div> + + + <h3><a name="hooking-add" id="hooking-add">Add a hook registering function</a></h3> + <p>During initialisation, Apache will call each modules hook + registering function, which is included in the module + structure:</p> + + <div class="example"><p><code> + static void my_register_hooks()<br /> + {<br /> + <span class="indent"> + ap_hook_do_something(my_something_doer, NULL, NULL, HOOK_MIDDLE);<br /> + </span> + }<br /> + <br /> + mode MODULE_VAR_EXPORT my_module =<br /> + {<br /> + <span class="indent"> + ...<br /> + my_register_hooks /* register hooks */<br /> + </span> + }; + </code></p></div> + + + <h3><a name="hooking-order" id="hooking-order">Controlling hook calling order</a></h3> + <p>In the example above, we didn't use the three arguments in + the hook registration function that control calling order. + There are two mechanisms for doing this. The first, rather + crude, method, allows us to specify roughly where the hook is + run relative to other modules. The final argument control this. + There are three possible values: <code>HOOK_FIRST</code>, + <code>HOOK_MIDDLE</code> and <code>HOOK_LAST</code>.</p> + + <p>All modules using any particular value may be run in any + order relative to each other, but, of course, all modules using + <code>HOOK_FIRST</code> will be run before <code>HOOK_MIDDLE</code> + which are before <code>HOOK_LAST</code>. Modules that don't care + when they are run should use <code>HOOK_MIDDLE</code>. <em>(I spaced + these out so people could do stuff like <code>HOOK_FIRST-2</code> + to get in slightly earlier, but is this wise? - Ben)</em></p> + + <p>Note that there are two more values, + <code>HOOK_REALLY_FIRST</code> and <code>HOOK_REALLY_LAST</code>. These + should only be used by the hook exporter.</p> + + <p>The other method allows finer control. When a module knows + that it must be run before (or after) some other modules, it + can specify them by name. The second (third) argument is a + NULL-terminated array of strings consisting of the names of + modules that must be run before (after) the current module. For + example, suppose we want "mod_xyz.c" and "mod_abc.c" to run + before we do, then we'd hook as follows:</p> + + <div class="example"><p><code> + static void register_hooks()<br /> + {<br /> + <span class="indent"> + static const char * const aszPre[] = { "mod_xyz.c", "mod_abc.c", NULL };<br /> + <br /> + ap_hook_do_something(my_something_doer, aszPre, NULL, HOOK_MIDDLE);<br /> + </span> + } + </code></p></div> + + <p>Note that the sort used to achieve this is stable, so + ordering set by <code>HOOK_<var>ORDER</var></code> is preserved, as far + as is possible.</p> + + <p class="cite"><cite>Ben Laurie</cite>, 15th August 1999</p> + +</div></div> +<div class="bottomlang"> +<p><span>Available Languages: </span><a href="../en/developer/hooks.html" title="English"> en </a></p> +</div><div id="footer"> +<p class="apache">Copyright 2009 The Apache Software Foundation.<br />Licensed under the <a href="http://www.apache.org/licenses/LICENSE-2.0">Apache License, Version 2.0</a>.</p> +<p class="menu"><a href="../mod/">Modules</a> | <a href="../mod/directives.html">Directives</a> | <a href="../faq/">FAQ</a> | <a href="../glossary.html">Glossary</a> | <a href="../sitemap.html">Sitemap</a></p></div> +</body></html>
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