359 lines
12 KiB
C
359 lines
12 KiB
C
/* Licensed to the Apache Software Foundation (ASF) under one or more
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* contributor license agreements. See the NOTICE file distributed with
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* this work for additional information regarding copyright ownership.
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* The ASF licenses this file to You under the Apache License, Version 2.0
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* (the "License"); you may not use this file except in compliance with
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* the License. You may obtain a copy of the License at
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*
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* http://www.apache.org/licenses/LICENSE-2.0
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*
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* Unless required by applicable law or agreed to in writing, software
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* distributed under the License is distributed on an "AS IS" BASIS,
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* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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* See the License for the specific language governing permissions and
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* limitations under the License.
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*/
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#ifndef APR_HOOKS_H
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#define APR_HOOKS_H
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#include "apu.h"
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/* For apr_array_header_t */
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#include "apr_tables.h"
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/**
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* @file apr_hooks.h
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* @brief Apache hook functions
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*/
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#ifdef __cplusplus
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extern "C" {
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#endif
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/**
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* @defgroup APR_Util_Hook Hook Functions
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* @ingroup APR_Util
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* @{
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*/
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/**
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* @defgroup apr_hook_probes Hook probe capability
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* APR hooks provide a trace probe capability for capturing
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* the flow of control and return values with hooks.
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*
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* In order to use this facility, the application must define
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* the symbol APR_HOOK_PROBES_ENABLED and the four APR_HOOK_PROBE_
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* macros described below before including apr_hooks.h in files
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* that use the APR_IMPLEMENT_EXTERNAL_HOOK_* macros.
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*
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* This probe facility is not provided for APR optional hooks.
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* @{
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*/
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#ifdef APR_HOOK_PROBES_ENABLED
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#define APR_HOOK_INT_DCL_UD void *ud = NULL
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#else
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/** internal implementation detail to avoid the ud declaration when
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* hook probes are not used
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*/
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#define APR_HOOK_INT_DCL_UD
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/**
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* User-defined hook probe macro that is invoked when the hook
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* is run, before calling any hook functions.
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* @param ud A void * user data field that should be filled in by
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* this macro, and will be provided to the other hook probe macros.
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* @param ns The namespace prefix of the hook functions
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* @param name The name of the hook
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* @param args The argument list to the hook functions, with enclosing
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* parens.
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*/
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#define APR_HOOK_PROBE_ENTRY(ud,ns,name,args)
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/**
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* User-defined hook probe macro that is invoked after the hook
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* has run.
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* @param ud A void * user data field that was filled in by the user-
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* provided APR_HOOK_PROBE_ENTRY().
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* @param ns The namespace prefix of the hook functions
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* @param name The name of the hook
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* @param rv The return value of the hook, or 0 if the hook is void.
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* @param args The argument list to the hook functions, with enclosing
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* parens.
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*/
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#define APR_HOOK_PROBE_RETURN(ud,ns,name,rv,args)
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/**
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* User-defined hook probe macro that is invoked before calling a
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* hook function.
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* @param ud A void * user data field that was filled in by the user-
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* provided APR_HOOK_PROBE_ENTRY().
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* @param ns The namespace prefix of the hook functions
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* @param name The name of the hook
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* @param src The value of apr_hook_debug_current at the time the function
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* was hooked (usually the source file implementing the hook function).
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* @param args The argument list to the hook functions, with enclosing
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* parens.
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*/
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#define APR_HOOK_PROBE_INVOKE(ud,ns,name,src,args)
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/**
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* User-defined hook probe macro that is invoked after calling a
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* hook function.
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* @param ud A void * user data field that was filled in by the user-
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* provided APR_HOOK_PROBE_ENTRY().
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* @param ns The namespace prefix of the hook functions
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* @param name The name of the hook
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* @param src The value of apr_hook_debug_current at the time the function
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* was hooked (usually the source file implementing the hook function).
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* @param rv The return value of the hook function, or 0 if the hook is void.
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* @param args The argument list to the hook functions, with enclosing
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* parens.
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*/
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#define APR_HOOK_PROBE_COMPLETE(ud,ns,name,src,rv,args)
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#endif
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/** @} */
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/** macro to return the prototype of the hook function */
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#define APR_IMPLEMENT_HOOK_GET_PROTO(ns,link,name) \
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link##_DECLARE(apr_array_header_t *) ns##_hook_get_##name(void)
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/** macro to declare the hook correctly */
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#define APR_DECLARE_EXTERNAL_HOOK(ns,link,ret,name,args) \
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typedef ret ns##_HOOK_##name##_t args; \
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link##_DECLARE(void) ns##_hook_##name(ns##_HOOK_##name##_t *pf, \
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const char * const *aszPre, \
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const char * const *aszSucc, int nOrder); \
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link##_DECLARE(ret) ns##_run_##name args; \
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APR_IMPLEMENT_HOOK_GET_PROTO(ns,link,name); \
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typedef struct ns##_LINK_##name##_t \
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{ \
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ns##_HOOK_##name##_t *pFunc; \
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const char *szName; \
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const char * const *aszPredecessors; \
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const char * const *aszSuccessors; \
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int nOrder; \
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} ns##_LINK_##name##_t;
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/** macro to declare the hook structure */
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#define APR_HOOK_STRUCT(members) \
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static struct { members } _hooks;
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/** macro to link the hook structure */
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#define APR_HOOK_LINK(name) \
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apr_array_header_t *link_##name;
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/** macro to implement the hook */
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#define APR_IMPLEMENT_EXTERNAL_HOOK_BASE(ns,link,name) \
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link##_DECLARE(void) ns##_hook_##name(ns##_HOOK_##name##_t *pf,const char * const *aszPre, \
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const char * const *aszSucc,int nOrder) \
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{ \
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ns##_LINK_##name##_t *pHook; \
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if(!_hooks.link_##name) \
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{ \
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_hooks.link_##name=apr_array_make(apr_hook_global_pool,1,sizeof(ns##_LINK_##name##_t)); \
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apr_hook_sort_register(#name,&_hooks.link_##name); \
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} \
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pHook=apr_array_push(_hooks.link_##name); \
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pHook->pFunc=pf; \
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pHook->aszPredecessors=aszPre; \
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pHook->aszSuccessors=aszSucc; \
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pHook->nOrder=nOrder; \
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pHook->szName=apr_hook_debug_current; \
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if(apr_hook_debug_enabled) \
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apr_hook_debug_show(#name,aszPre,aszSucc); \
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} \
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APR_IMPLEMENT_HOOK_GET_PROTO(ns,link,name) \
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{ \
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return _hooks.link_##name; \
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}
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/**
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* Implement a hook that has no return code, and therefore runs all of the
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* registered functions
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* @param ns The namespace prefix of the hook functions
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* @param link The linkage declaration prefix of the hook
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* @param name The name of the hook
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* @param args_decl The declaration of the arguments for the hook
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* @param args_use The names for the arguments for the hook
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* @note The link prefix FOO corresponds to FOO_DECLARE() macros, which
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* provide export linkage from the module that IMPLEMENTs the hook, and
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* import linkage from external modules that link to the hook's module.
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*/
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#define APR_IMPLEMENT_EXTERNAL_HOOK_VOID(ns,link,name,args_decl,args_use) \
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APR_IMPLEMENT_EXTERNAL_HOOK_BASE(ns,link,name) \
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link##_DECLARE(void) ns##_run_##name args_decl \
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{ \
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ns##_LINK_##name##_t *pHook; \
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int n; \
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APR_HOOK_INT_DCL_UD; \
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\
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APR_HOOK_PROBE_ENTRY(ud, ns, name, args_use); \
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\
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if(_hooks.link_##name) \
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{ \
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pHook=(ns##_LINK_##name##_t *)_hooks.link_##name->elts; \
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for(n=0 ; n < _hooks.link_##name->nelts ; ++n) \
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{ \
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APR_HOOK_PROBE_INVOKE(ud, ns, name, (char *)pHook[n].szName, args_use); \
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pHook[n].pFunc args_use; \
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APR_HOOK_PROBE_COMPLETE(ud, ns, name, (char *)pHook[n].szName, 0, args_use); \
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} \
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} \
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\
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APR_HOOK_PROBE_RETURN(ud, ns, name, 0, args_use); \
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\
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}
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/* FIXME: note that this returns ok when nothing is run. I suspect it should
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really return decline, but that breaks Apache currently - Ben
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*/
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/**
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* Implement a hook that runs until one of the functions returns something
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* other than OK or DECLINE
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* @param ns The namespace prefix of the hook functions
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* @param link The linkage declaration prefix of the hook
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* @param ret Type to return
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* @param name The name of the hook
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* @param args_decl The declaration of the arguments for the hook
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* @param args_use The names for the arguments for the hook
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* @param ok Success value
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* @param decline Decline value
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* @note The link prefix FOO corresponds to FOO_DECLARE() macros, which
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* provide export linkage from the module that IMPLEMENTs the hook, and
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* import linkage from external modules that link to the hook's module.
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*/
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#define APR_IMPLEMENT_EXTERNAL_HOOK_RUN_ALL(ns,link,ret,name,args_decl,args_use,ok,decline) \
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APR_IMPLEMENT_EXTERNAL_HOOK_BASE(ns,link,name) \
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link##_DECLARE(ret) ns##_run_##name args_decl \
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{ \
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ns##_LINK_##name##_t *pHook; \
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int n; \
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ret rv = ok; \
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APR_HOOK_INT_DCL_UD; \
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\
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APR_HOOK_PROBE_ENTRY(ud, ns, name, args_use); \
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\
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if(_hooks.link_##name) \
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{ \
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pHook=(ns##_LINK_##name##_t *)_hooks.link_##name->elts; \
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for(n=0 ; n < _hooks.link_##name->nelts ; ++n) \
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{ \
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APR_HOOK_PROBE_INVOKE(ud, ns, name, (char *)pHook[n].szName, args_use); \
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rv=pHook[n].pFunc args_use; \
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APR_HOOK_PROBE_COMPLETE(ud, ns, name, (char *)pHook[n].szName, rv, args_use); \
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if(rv != ok && rv != decline) \
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break; \
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rv = ok; \
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} \
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} \
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\
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APR_HOOK_PROBE_RETURN(ud, ns, name, rv, args_use); \
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\
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return rv; \
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}
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/**
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* Implement a hook that runs until the first function returns something
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* other than the value of decline
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* @param ns The namespace prefix of the hook functions
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* @param link The linkage declaration prefix of the hook
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* @param name The name of the hook
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* @param ret Type to return
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* @param args_decl The declaration of the arguments for the hook
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* @param args_use The names for the arguments for the hook
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* @param decline Decline value
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* @note The link prefix FOO corresponds to FOO_DECLARE() macros, which
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* provide export linkage from the module that IMPLEMENTs the hook, and
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* import linkage from external modules that link to the hook's module.
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*/
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#define APR_IMPLEMENT_EXTERNAL_HOOK_RUN_FIRST(ns,link,ret,name,args_decl,args_use,decline) \
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APR_IMPLEMENT_EXTERNAL_HOOK_BASE(ns,link,name) \
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link##_DECLARE(ret) ns##_run_##name args_decl \
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{ \
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ns##_LINK_##name##_t *pHook; \
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int n; \
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ret rv = decline; \
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APR_HOOK_INT_DCL_UD; \
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\
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APR_HOOK_PROBE_ENTRY(ud, ns, name, args_use); \
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\
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if(_hooks.link_##name) \
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{ \
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pHook=(ns##_LINK_##name##_t *)_hooks.link_##name->elts; \
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for(n=0 ; n < _hooks.link_##name->nelts ; ++n) \
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{ \
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APR_HOOK_PROBE_INVOKE(ud, ns, name, (char *)pHook[n].szName, args_use); \
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rv=pHook[n].pFunc args_use; \
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APR_HOOK_PROBE_COMPLETE(ud, ns, name, (char *)pHook[n].szName, rv, args_use); \
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\
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if(rv != decline) \
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break; \
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} \
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} \
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\
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APR_HOOK_PROBE_RETURN(ud, ns, name, rv, args_use); \
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\
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return rv; \
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}
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/* Hook orderings */
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/** run this hook first, before ANYTHING */
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#define APR_HOOK_REALLY_FIRST (-10)
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/** run this hook first */
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#define APR_HOOK_FIRST 0
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/** run this hook somewhere */
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#define APR_HOOK_MIDDLE 10
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/** run this hook after every other hook which is defined*/
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#define APR_HOOK_LAST 20
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/** run this hook last, after EVERYTHING */
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#define APR_HOOK_REALLY_LAST 30
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/**
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* The global pool used to allocate any memory needed by the hooks.
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*/
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APU_DECLARE_DATA extern apr_pool_t *apr_hook_global_pool;
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/**
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* A global variable to determine if debugging information about the
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* hooks functions should be printed.
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*/
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APU_DECLARE_DATA extern int apr_hook_debug_enabled;
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/**
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* The name of the module that is currently registering a function.
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*/
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APU_DECLARE_DATA extern const char *apr_hook_debug_current;
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/**
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* Register a hook function to be sorted.
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* @param szHookName The name of the Hook the function is registered for
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* @param aHooks The array which stores all of the functions for this hook
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*/
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APU_DECLARE(void) apr_hook_sort_register(const char *szHookName,
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apr_array_header_t **aHooks);
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/**
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* Sort all of the registered functions for a given hook.
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*/
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APU_DECLARE(void) apr_hook_sort_all(void);
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/**
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* Print all of the information about the current hook. This is used for
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* debugging purposes.
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* @param szName The name of the hook
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* @param aszPre All of the functions in the predecessor array
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* @param aszSucc All of the functions in the successor array
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*/
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APU_DECLARE(void) apr_hook_debug_show(const char *szName,
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const char * const *aszPre,
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const char * const *aszSucc);
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/**
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* Remove all currently registered functions.
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*/
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APU_DECLARE(void) apr_hook_deregister_all(void);
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/** @} */
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#ifdef __cplusplus
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}
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#endif
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#endif /* APR_HOOKS_H */
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