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Diffstat (limited to 'include/apr_hooks.h')
| -rw-r--r-- | include/apr_hooks.h | 358 |
1 files changed, 358 insertions, 0 deletions
diff --git a/include/apr_hooks.h b/include/apr_hooks.h new file mode 100644 index 0000000..b675711 --- /dev/null +++ b/include/apr_hooks.h @@ -0,0 +1,358 @@ +/* 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 registerd 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 */ |