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authorDaniel Baumann <daniel.baumann@progress-linux.org>2024-04-07 15:01:30 +0000
committerDaniel Baumann <daniel.baumann@progress-linux.org>2024-04-07 15:01:30 +0000
commit6beeb1b708550be0d4a53b272283e17e5e35fe17 (patch)
tree1ce8673d4aaa948e5554000101f46536a1e4cc29 /docs/manual/developer/new_api_2_4.html.en
parentInitial commit. (diff)
downloadapache2-6beeb1b708550be0d4a53b272283e17e5e35fe17.tar.xz
apache2-6beeb1b708550be0d4a53b272283e17e5e35fe17.zip
Adding upstream version 2.4.57.upstream/2.4.57upstream
Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>
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+<?xml version="1.0" encoding="UTF-8"?>
+<!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>
+<meta content="text/html; charset=UTF-8" http-equiv="Content-Type" />
+<!--
+ XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX
+ This file is generated from xml source: DO NOT EDIT
+ XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX
+ -->
+<title>API Changes in Apache HTTP Server 2.4 since 2.2 - Apache HTTP Server Version 2.4</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 rel="stylesheet" type="text/css" href="../style/css/prettify.css" />
+<script src="../style/scripts/prettify.min.js" type="text/javascript">
+</script>
+
+<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="http://wiki.apache.org/httpd/FAQ">FAQ</a> | <a href="../glossary.html">Glossary</a> | <a href="../sitemap.html">Sitemap</a></p>
+<p class="apache">Apache HTTP Server Version 2.4</p>
+<img alt="" src="../images/feather.png" /></div>
+<div class="up"><a href="./"><img title="&lt;-" alt="&lt;-" src="../images/left.gif" /></a></div>
+<div id="path">
+<a href="http://www.apache.org/">Apache</a> &gt; <a href="http://httpd.apache.org/">HTTP Server</a> &gt; <a href="http://httpd.apache.org/docs/">Documentation</a> &gt; <a href="../">Version 2.4</a></div><div id="page-content"><div id="preamble"><h1>API Changes in Apache HTTP Server 2.4 since 2.2</h1>
+<div class="toplang">
+<p><span>Available Languages: </span><a href="../en/developer/new_api_2_4.html" title="English">&nbsp;en&nbsp;</a></p>
+</div>
+
+ <p>This document describes changes to the Apache HTTPD API from
+ version 2.2 to 2.4, that may be of interest to module/application
+ developers and core hacks. As of the first GA release of the
+ 2.4 branch API compatibility is preserved for the life of the
+ 2.4 branch. (The
+ <a href="http://svn.apache.org/repos/asf/httpd/httpd/branches/2.4.x/VERSIONING">VERSIONING</a>
+ description for the 2.4 release provides more information about API
+ compatibility.)</p>
+
+ <p>API changes fall into two categories: APIs that are altogether new,
+ and existing APIs that are expanded or changed. The latter are
+ further divided into those where all changes are backwards-compatible
+ (so existing modules can ignore them), and those that might
+ require attention by maintainers. As with the transition from
+ HTTPD 2.0 to 2.2, existing modules and applications will require
+ recompiling and may call for some attention, but most should not
+ require any substantial updating (although some may be able to
+ take advantage of API changes to offer significant improvements).</p>
+ <p>For the purpose of this document, the API is split according
+ to the public header files. These headers are themselves the
+ reference documentation, and can be used to generate a browsable
+ HTML reference with <code>make docs</code>.</p>
+</div>
+<div id="quickview"><a href="https://www.apache.org/foundation/contributing.html" class="badge"><img src="https://www.apache.org/images/SupportApache-small.png" alt="Support Apache!" /></a><ul id="toc"><li><img alt="" src="../images/down.gif" /> <a href="#api_changes">Changed APIs</a></li>
+<li><img alt="" src="../images/down.gif" /> <a href="#upgrading">Specific information on upgrading modules from 2.2</a></li>
+</ul><h3>See also</h3><ul class="seealso"><li><a href="#comments_section">Comments</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="api_changes" id="api_changes">Changed APIs</a></h2>
+
+
+ <h3><a name="ap_expr" id="ap_expr">ap_expr (NEW!)</a></h3>
+
+ <p>Introduces a new API to parse and evaluate boolean and algebraic
+ expressions, including provision for a standard syntax and
+ customised variants.</p>
+
+
+ <h3><a name="ap_listen" id="ap_listen">ap_listen (changed; backwards-compatible)</a></h3>
+
+ <p>Introduces a new API to enable httpd child processes to serve
+ different purposes.</p>
+
+
+ <h3><a name="ap_mpm" id="ap_mpm">ap_mpm (changed)</a></h3>
+
+ <p><code>ap_mpm_run</code> is replaced by a new <code>mpm</code> hook.
+ Also <code>ap_graceful_stop_signalled</code> is lost, and
+ <code>ap_mpm_register_timed_callback</code> is new.</p>
+
+
+ <h3><a name="ap_regex" id="ap_regex">ap_regex (changed)</a></h3>
+
+ <p>In addition to the existing regexp wrapper, a new higher-level API
+ <code>ap_rxplus</code> is now provided. This provides the capability to
+ compile Perl-style expressions like <code>s/regexp/replacement/flags</code>
+ and to execute them against arbitrary strings. Support for regexp
+ backreferences is also added.</p>
+
+
+ <h3><a name="ap_slotmem" id="ap_slotmem">ap_slotmem (NEW!)</a></h3>
+
+ <p>Introduces an API for modules to allocate and manage memory slots,
+ most commonly for shared memory.</p>
+
+
+ <h3><a name="ap_socache" id="ap_socache">ap_socache (NEW!)</a></h3>
+
+ <p>API to manage a shared object cache.</p>
+
+
+ <h3><a name="heartbeat" id="heartbeat">heartbeat (NEW!)</a></h3>
+
+ <p>common structures for heartbeat modules</p>
+
+
+ <h3><a name="ap_parse_htaccess" id="ap_parse_htaccess">ap_parse_htaccess (changed)</a></h3>
+
+ <p>The function signature for <code>ap_parse_htaccess</code> has been
+ changed. A <code>apr_table_t</code> of individual directives allowed
+ for override must now be passed (override remains).</p>
+
+
+ <h3><a name="http_config" id="http_config">http_config (changed)</a></h3>
+
+ <ul>
+ <li>Introduces per-module, per-directory loglevels, including macro wrappers.</li>
+ <li>New <code>AP_DECLARE_MODULE</code> macro to declare all modules.</li>
+ <li>New <code>APLOG_USE_MODULE</code> macro necessary for per-module loglevels in
+ multi-file modules.</li>
+ <li>New API to retain data across module unload/load</li>
+ <li>New <code>check_config</code> hook</li>
+ <li>New <code>ap_process_fnmatch_configs()</code> function to process wildcards</li>
+ <li>Change <code>ap_configfile_t</code>, <code>ap_cfg_getline()</code>,
+ <code>ap_cfg_getc()</code> to return error codes, and add
+ <code>ap_pcfg_strerror()</code> for retrieving an error description.</li>
+ <li>Any config directive permitted in ACCESS_CONF context must now
+ correctly handle being called from an .htaccess file via the new
+ <code class="directive"><a href="../mod/core.html#allowoverridelist">AllowOverrideList</a></code> directive.
+ ap_check_cmd_context() accepts a new flag NOT_IN_HTACCESS to detect
+ this case.</li>
+ </ul>
+
+
+ <h3><a name="http_core" id="http_core">http_core (changed)</a></h3>
+
+ <ul>
+ <li>REMOVED <code>ap_default_type</code>, <code>ap_requires</code>, all
+ 2.2 authnz API</li>
+ <li>Introduces Optional Functions for logio and authnz</li>
+ <li>New function <code>ap_get_server_name_for_url</code> to support IPv6
+ literals.</li>
+ <li>New function <code>ap_register_errorlog_handler</code> to register error log
+ format string handlers.</li>
+ <li>Arguments of <code>error_log</code> hook have changed. Declaration has moved to
+ <code>http_core.h</code>.</li>
+ <li>New function <code>ap_state_query</code> to determine if the server is in the
+ initial configuration preflight phase or not. This is both easier to
+ use and more correct than the old method of creating a pool userdata
+ entry in the process pool.</li>
+ <li>New function <code>ap_get_conn_socket</code> to get the socket descriptor for a
+ connection. This should be used instead of accessing the core
+ connection config directly.</li>
+ </ul>
+
+
+ <h3><a name="httpd" id="httpd">httpd (changed)</a></h3>
+
+ <ul>
+ <li>Introduce per-directory, per-module loglevel</li>
+ <li>New loglevels <code>APLOG_TRACEn</code></li>
+ <li>Introduce errorlog ids for requests and connections</li>
+ <li>Support for mod_request kept_body</li>
+ <li>Support buffering filter data for async requests</li>
+ <li>New <code>CONN_STATE</code> values</li>
+ <li>Function changes: <code>ap_escape_html</code> updated;
+ <code>ap_unescape_all</code>, <code>ap_escape_path_segment_buffer</code></li>
+ <li>Modules that load other modules later than the <code>EXEC_ON_READ</code> config
+ reading stage need to call <code>ap_reserve_module_slots()</code> or
+ <code>ap_reserve_module_slots_directive()</code> in their
+ <code>pre_config hook</code>.</li>
+ <li>The useragent IP address per request can now be tracked
+ independently of the client IP address of the connection, for
+ support of deployments with load balancers.</li>
+ </ul>
+
+
+ <h3><a name="http_log" id="http_log">http_log (changed)</a></h3>
+
+ <ul>
+ <li>Introduce per-directory, per-module loglevel</li>
+ <li>New loglevels <code>APLOG_TRACEn</code></li>
+ <li><code>ap_log_*error</code> become macro wrappers (backwards-compatible if
+ <code>APLOG_MARK</code> macro is used, except that is no longer possible to
+ use <code>#ifdef</code> inside the argument list)</li>
+ <li>piped logging revamped</li>
+ <li><code>module_index</code> added to error_log hook</li>
+ <li>new function: <code>ap_log_command_line</code></li>
+ </ul>
+
+
+ <h3><a name="http_request" id="http_request">http_request (changed)</a></h3>
+
+ <ul>
+ <li>New auth_internal API and auth_provider API</li>
+ <li>New <code>EOR</code> bucket type</li>
+ <li>New function <code>ap_process_async_request</code></li>
+ <li>New flags <code>AP_AUTH_INTERNAL_PER_CONF</code> and
+ <code>AP_AUTH_INTERNAL_PER_URI</code></li>
+ <li>New <code>access_checker_ex</code> hook to apply additional access control
+ and/or bypass authentication.</li>
+ <li>New functions <code>ap_hook_check_access_ex</code>,
+ <code>ap_hook_check_access</code>, <code>ap_hook_check_authn</code>,
+ <code>ap_hook_check_authz</code> which accept
+ <code>AP_AUTH_INTERNAL_PER_*</code> flags</li>
+ <li>DEPRECATED direct use of <code>ap_hook_access_checker</code>,
+ <code>access_checker_ex</code>, <code>ap_hook_check_user_id</code>,
+ <code>ap_hook_auth_checker</code></li>
+ </ul>
+ <p>When possible, registering all access control hooks (including
+ authentication and authorization hooks) using <code>AP_AUTH_INTERNAL_PER_CONF</code>
+ is recommended. If all modules' access control hooks are registered
+ with this flag, then whenever the server handles an internal
+ sub-request that matches the same set of access control configuration
+ directives as the initial request (which is the common case), it can
+ avoid invoking the access control hooks another time.</p>
+ <p>If your module requires the old behavior and must perform access
+ control checks on every sub-request with a different URI from the
+ initial request, even if that URI matches the same set of access
+ control configuration directives, then use
+ <code>AP_AUTH_INTERNAL_PER_URI</code>.</p>
+
+
+ <h3><a name="mod_auth" id="mod_auth">mod_auth (NEW!)</a></h3>
+
+ <p>Introduces the new provider framework for authn and authz</p>
+
+
+ <h3><a name="mod_cache" id="mod_cache">mod_cache (changed)</a></h3>
+
+ <p>Introduces a <code>commit_entity()</code> function to the cache provider
+ interface, allowing atomic writes to cache. Add a <code>cache_status()</code>
+ hook to report the cache decision. All private structures and functions were
+ removed.</p>
+
+
+ <h3><a name="mod_core" id="mod_core">mod_core (NEW!)</a></h3>
+
+ <p>This introduces low-level APIs to send arbitrary headers,
+ and exposes functions to handle HTTP OPTIONS and TRACE.</p>
+
+
+ <h3><a name="mod_cache_disk" id="mod_cache_disk">mod_cache_disk (changed)</a></h3>
+
+ <p>Changes the disk format of the disk cache to support atomic cache
+ updates without locking. The device/inode pair of the body file is
+ embedded in the header file, allowing confirmation that the header
+ and body belong to one another.</p>
+
+
+ <h3><a name="mod_disk_cache" id="mod_disk_cache">mod_disk_cache (renamed)</a></h3>
+
+ <p>The mod_disk_cache module has been renamed to mod_cache_disk in
+ order to be consistent with the naming of other modules within the
+ server.</p>
+
+
+ <h3><a name="mod_request" id="mod_request">mod_request (NEW!)</a></h3>
+
+ <p>The API for <code class="module"><a href="../mod/mod_request.html">mod_request</a></code>, to make input data
+ available to multiple application/handler modules where required,
+ and to parse HTML form data.</p>
+
+
+ <h3><a name="mpm_common" id="mpm_common">mpm_common (changed)</a></h3>
+
+ <ul>
+ <li>REMOVES: <code>accept</code>, <code>lockfile</code>, <code>lock_mech</code>,
+ <code>set_scoreboard</code> (locking uses the new ap_mutex API)</li>
+ <li>NEW API to drop privileges (delegates this platform-dependent
+ function to modules)</li>
+ <li>NEW Hooks: <code>mpm_query</code>, <code>timed_callback</code>, and
+ <code>get_name</code></li>
+ <li>CHANGED interfaces: <code>monitor</code> hook,
+ <code>ap_reclaim_child_processes</code>,
+ <code>ap_relieve_child_processes</code></li>
+ </ul>
+
+
+ <h3><a name="scoreboard" id="scoreboard">scoreboard (changed)</a></h3>
+
+ <p><code>ap_get_scoreboard_worker</code> is made non-backwards-compatible
+ as an alternative version is introduced. Additional proxy_balancer
+ support. Child status stuff revamped.</p>
+
+
+ <h3><a name="util_cookies" id="util_cookies">util_cookies (NEW!)</a></h3>
+
+ <p>Introduces a new API for managing HTTP Cookies.</p>
+
+
+ <h3><a name="util_ldap" id="util_ldap">util_ldap (changed)</a></h3>
+
+ <p><em>no description available</em></p>
+
+
+ <h3><a name="util_mutex" id="util_mutex">util_mutex (NEW!)</a></h3>
+
+ <p>A wrapper for APR proc and global mutexes in httpd, providing
+ common configuration for the underlying mechanism and location
+ of lock files.</p>
+
+
+ <h3><a name="util_script" id="util_script">util_script (changed)</a></h3>
+
+ <p>NEW: <code>ap_args_to_table</code></p>
+
+
+ <h3><a name="util_time" id="util_time">util_time (changed)</a></h3>
+
+ <p>NEW: <code>ap_recent_ctime_ex</code></p>
+
+
+</div><div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div>
+<div class="section">
+<h2><a name="upgrading" id="upgrading">Specific information on upgrading modules from 2.2</a></h2>
+
+
+ <h3><a name="upgrading_logging" id="upgrading_logging">Logging</a></h3>
+
+ <p>In order to take advantage of per-module loglevel configuration, any
+ source file that calls the <code>ap_log_*</code> functions should declare
+ which module it belongs to. If the module's module_struct is called
+ <code>foo_module</code>, the following code can be used to remain
+ backward compatible with HTTPD 2.0 and 2.2:</p>
+ <div class="example"><p><code>
+ #include &lt;http_log.h&gt;<br />
+ <br />
+ #ifdef APLOG_USE_MODULE<br />
+ APLOG_USE_MODULE(foo);<br />
+ #endif
+ </code></p></div>
+ <p>Note: This is absolutely required for C++-language modules. It
+ can be skipped for C-language modules, though that breaks
+ module-specific log level support for files without it.</p>
+ <p>The number of parameters of the <code>ap_log_*</code> functions and the
+ definition of <code>APLOG_MARK</code> has changed. Normally, the change
+ is completely transparent. However, changes are required if a
+ module uses <code>APLOG_MARK</code> as a parameter to its own functions
+ or if a module calls <code>ap_log_*</code> without passing
+ <code>APLOG_MARK</code>. A module which uses wrappers
+ around <code>ap_log_*</code> typically uses both of these constructs.</p>
+
+ <p>The easiest way to change code which passes <code>APLOG_MARK</code> to
+ its own functions is to define and use a different macro that expands to
+ the parameters required by those functions, as <code>APLOG_MARK</code>
+ should only be used when calling <code>ap_log_*</code>
+ directly. In this way, the code will remain compatible with HTTPD 2.0
+ and 2.2.</p>
+
+ <p>Code which calls <code>ap_log_*</code> without passing
+ <code>APLOG_MARK</code> will necessarily differ between 2.4 and earlier
+ releases, as 2.4 requires a new third argument,
+ <code>APLOG_MODULE_INDEX</code>.</p>
+
+ <div class="example"><p><code>
+ /* code for httpd 2.0/2.2 */<br />
+ ap_log_perror(file, line, APLOG_ERR, 0, p, "Failed to allocate dynamic lock structure");<br />
+ <br />
+ /* code for httpd 2.4 */<br />
+ ap_log_perror(file, line, APLOG_MODULE_INDEX, APLOG_ERR, 0, p, "Failed to allocate dynamic lock structure");<br />
+ <br />
+ </code></p></div>
+
+ <p><code>ap_log_*error</code> are now implemented as macros. This means
+ that it is no longer possible to use <code>#ifdef</code> inside the
+ argument list of <code>ap_log_*error</code>, as this would cause
+ undefined behavior according to C99.</p>
+
+ <p>A <code>server_rec</code> pointer must be passed to
+ <code>ap_log_error()</code> when called after startup. This
+ was always appropriate, but there are even more limitations with
+ a <code>NULL</code> <code>server_rec</code> in 2.4 than in
+ previous releases. Beginning with 2.3.12, the global variable
+ <code>ap_server_conf</code> can always be used as
+ the <code>server_rec</code> parameter, as it will be
+ <code>NULL</code> only when it is valid to pass <code>NULL</code>
+ to <code>ap_log_error()</code>. <code>ap_server_conf</code>
+ should be used only when a more appropriate <code>server_rec</code>
+ is not available.</p>
+
+ <p>Consider the following changes to take advantage of the new
+ <code>APLOG_TRACE1..8</code> log levels:</p>
+ <ul>
+ <li>Check current use of <code>APLOG_DEBUG</code> and
+ consider if one of the <code>APLOG_TRACEn</code> levels is
+ more appropriate.</li>
+ <li>If your module currently has a mechanism for configuring
+ the amount of debug logging which is performed, consider
+ eliminating that mechanism and relying on the use of
+ different <code>APLOG_TRACEn</code> levels. If expensive
+ trace processing needs to be bypassed depending on the
+ configured log level, use the <code>APLOGtrace<em>n</em></code>
+ and <code>APLOGrtrace<em>n</em></code> macros to first check
+ if tracing is enabled.</li>
+ </ul>
+
+ <p>Modules sometimes add process id and/or thread id to their log
+ messages. These ids are now logged by default, so it may not
+ be necessary for the module to log them explicitly. (Users may
+ remove them from the error log format, but they can be
+ instructed to add it back if necessary for problem diagnosis.)</p>
+
+
+ <h3><a name="upgrading_byfunction" id="upgrading_byfunction">If your module uses these existing APIs...</a></h3>
+
+
+ <dl>
+ <dt><code>ap_default_type()</code></dt>
+ <dd>This is no longer available; Content-Type must be configured
+ explicitly or added by the application.</dd>
+
+ <dt><code>ap_get_server_name()</code></dt>
+ <dd>If the returned server name is used in a URL,
+ use <code>ap_get_server_name_for_url()</code> instead. This new
+ function handles the odd case where the server name is an IPv6
+ literal address.</dd>
+
+ <dt><code>ap_get_server_version()</code></dt>
+ <dd>For logging purposes, where detailed information is
+ appropriate, use <code>ap_get_server_description()</code>.
+ When generating output, where the amount of information
+ should be configurable by ServerTokens, use
+ <code>ap_get_server_banner()</code>.</dd>
+
+ <dt><code>ap_graceful_stop_signalled()</code></dt>
+ <dd>Replace with a call
+ to <code>ap_mpm_query(AP_MPMQ_MPM_STATE)</code> and checking for
+ state <code>AP_MPMQ_STOPPING</code>.</dd>
+
+ <dt><code>ap_max_daemons_limit</code>, <code>ap_my_generation</code>,
+ and <code>ap_threads_per_child</code></dt>
+ <dd>Use <code>ap_mpm_query()</code> query codes
+ <code>AP_MPMQ_MAX_DAEMON_USED</code>, <code>AP_MPMQ_GENERATION</code>,
+ and <code>AP_MPMQ_MAX_THREADS</code>, respectively.</dd>
+
+ <dt><code>ap_mpm_query()</code></dt>
+ <dd>Ensure that it is not used until after the register-hooks
+ hook has completed. Otherwise, an MPM built as a DSO
+ would not have had a chance to enable support for this
+ function.</dd>
+
+ <dt><code>ap_requires()</code></dt>
+ <dd>The core server now provides better infrastructure for handling
+ <code class="directive"><a href="../mod/mod_authz_core.html#require">Require</a></code> configuration.
+ Register an auth provider function for each supported entity using
+ <code>ap_register_auth_provider()</code>. The function will be
+ called as necessary during <code class="directive">Require</code>
+ processing. (Consult bundled modules for detailed examples.)</dd>
+
+ <dt><code>ap_server_conf-&gt;process-&gt;pool</code>
+ userdata</dt>
+ <dd>
+ Optional:
+ <ul>
+ <li>If your module uses this to determine which pass of the
+ startup hooks is being run,
+ use <code>ap_state_query(AP_SQ_MAIN_STATE)</code>.</li>
+ <li>If your module uses this to maintain data across the
+ unloading and reloading of your module, use
+ <code>ap_retained_data_create()</code> and
+ <code>ap_retained_data_get()</code>.</li>
+ </ul>
+ </dd>
+
+ <dt><code>apr_global_mutex_create()</code>,
+ <code>apr_proc_mutex_create()</code></dt>
+ <dd>Optional: See <code>ap_mutex_register()</code>,
+ <code>ap_global_mutex_create()</code>, and
+ <code>ap_proc_mutex_create()</code>; these allow your
+ mutexes to be configurable with
+ the <code class="directive"><a href="../mod/core.html#mutex">Mutex</a></code> directive;
+ you can also remove any configuration mechanisms in your
+ module for such mutexes
+ </dd>
+
+ <dt><code>CORE_PRIVATE</code></dt>
+ <dd>This is now unnecessary and ignored.</dd>
+
+ <dt><code>dav_new_error()</code>
+ and <code>dav_new_error_tag()</code></dt>
+ <dd>Previously, these assumed that <code>errno</code> contained
+ information describing the failure. Now,
+ an <code>apr_status_t</code> parameter must be provided. Pass
+ 0/APR_SUCCESS if there is no such error information, or a valid
+ <code>apr_status_t</code> value otherwise.</dd>
+
+ <dt><code>mpm_default.h</code>, <code>DEFAULT_LOCKFILE</code>,
+ <code>DEFAULT_THREAD_LIMIT</code>, <code>DEFAULT_PIDLOG</code>,
+ etc.</dt>
+ <dd>The header file and most of the default configuration
+ values set in it are no longer visible to modules. (Most can
+ still be overridden at build time.) <code>DEFAULT_PIDLOG</code>
+ and <code>DEFAULT_REL_RUNTIMEDIR</code> are now universally
+ available via <code>ap_config.h</code>.</dd>
+
+ <dt><code>unixd_config</code></dt>
+ <dd>This has been renamed to ap_unixd_config.</dd>
+
+ <dt><code>unixd_setup_child()</code></dt>
+ <dd>This has been renamed to ap_unixd_setup_child(), but most callers
+ should call the added ap_run_drop_privileges() hook.</dd>
+
+ <dt><code>conn_rec-&gt;remote_ip</code> and
+ <code>conn_rec-&gt;remote_addr</code></dt>
+ <dd>These fields have been renamed in order to distinguish between
+ the client IP address of the connection and the useragent IP address
+ of the request (potentially overridden by a load balancer or proxy).
+ References to either of these fields must be updated with one of the
+ following options, as appropriate for the module:
+ <ul>
+ <li>When you require the IP address of the user agent, which
+ might be connected directly to the server, or might optionally be
+ separated from the server by a transparent load balancer or
+ proxy, use <code>request_rec-&gt;useragent_ip</code> and
+ <code>request_rec-&gt;useragent_addr</code>.</li>
+ <li>When you require the IP address of the client that is
+ connected directly to the server, which might be the useragent or
+ might be the load balancer or proxy itself, use
+ <code>conn_rec-&gt;client_ip</code> and
+ <code>conn_rec-&gt;client_addr</code>.</li>
+ </ul>
+ </dd>
+ </dl>
+
+
+ <h3><a name="upgrading_byfeature" id="upgrading_byfeature">If your module interfaces with this feature...</a></h3>
+
+ <dl>
+ <dt>suEXEC</dt>
+ <dd>Optional: If your module logs an error
+ when <code>ap_unixd_config.suexec_enabled</code> is 0,
+ also log the value of the new
+ field <code>suexec_disabled_reason</code>, which contains an
+ explanation of why it is not available.</dd>
+
+ <dt>Extended status data in the scoreboard</dt>
+ <dd>In previous releases, <code>ExtendedStatus</code> had to be
+ set to <code>On</code>, which in turn required that
+ mod_status was loaded. In 2.4, just
+ set <code>ap_extended_status</code> to <code>1</code> in a
+ pre-config hook and the extended status data will be
+ available.</dd>
+ </dl>
+
+
+ <h3><a name="upgrading_newfeatures" id="upgrading_newfeatures">Does your module...</a></h3>
+
+ <dl>
+ <dt>Parse query args</dt>
+ <dd>Consider if <code>ap_args_to_table()</code> would be
+ helpful.</dd>
+
+ <dt>Parse form data...</dt>
+ <dd>Use <code>ap_parse_form_data()</code>.</dd>
+
+ <dt>Check for request header fields <code>Content-Length</code>
+ and <code>Transfer-Encoding</code> to see if a body was
+ specified</dt>
+ <dd>Use <code>ap_request_has_body()</code>.</dd>
+
+ <dt>Implement cleanups which clear pointer variables</dt>
+ <dd>Use <code>ap_pool_cleanup_set_null()</code>.</dd>
+
+ <dt>Create run-time files such as shared memory files, pid files,
+ etc.</dt>
+ <dd>Use <code>ap_runtime_dir_relative()</code> so that the global
+ configuration for the location of such files, either by the
+ <code>DEFAULT_REL_RUNTIMEDIR</code> compile setting or the
+ <code class="directive"><a href="../mod/core.html#defaultruntimedir">DefaultRuntimeDir</a></code> directive,
+ will be respected. <em>Apache httpd 2.4.2 and above.</em></dd>
+
+ </dl>
+
+
+</div></div>
+<div class="bottomlang">
+<p><span>Available Languages: </span><a href="../en/developer/new_api_2_4.html" title="English">&nbsp;en&nbsp;</a></p>
+</div><div class="top"><a href="#page-header"><img src="../images/up.gif" alt="top" /></a></div><div class="section"><h2><a id="comments_section" name="comments_section">Comments</a></h2><div class="warning"><strong>Notice:</strong><br />This is not a Q&amp;A section. Comments placed here should be pointed towards suggestions on improving the documentation or server, and may be removed by our moderators if they are either implemented or considered invalid/off-topic. Questions on how to manage the Apache HTTP Server should be directed at either our IRC channel, #httpd, on Libera.chat, or sent to our <a href="https://httpd.apache.org/lists.html">mailing lists</a>.</div>
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