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