Hook Functions
[APR Utility Functions]

Modules
	Optional Hook Functions
Defines
#define	APR_IMPLEMENT_HOOK_GET_PROTO(ns, link, name)   link##_DECLARE(apr_array_header_t *) ns##_hook_get_##name(void)
#define	APR_DECLARE_EXTERNAL_HOOK(ns, link, ret, name, args)
#define	APR_HOOK_STRUCT(members)   static struct { members } _hooks;
#define	APR_HOOK_LINK(name)   apr_array_header_t *link_##name;
#define	APR_IMPLEMENT_EXTERNAL_HOOK_BASE(ns, link, name)
#define	APR_IMPLEMENT_EXTERNAL_HOOK_VOID(ns, link, name, args_decl, args_use)
#define	APR_IMPLEMENT_EXTERNAL_HOOK_RUN_ALL(ns, link, ret, name, args_decl, args_use, ok, decline)
#define	APR_IMPLEMENT_EXTERNAL_HOOK_RUN_FIRST(ns, link, ret, name, args_decl, args_use, decline)
#define	APR_HOOK_REALLY_FIRST   (-10)
#define	APR_HOOK_FIRST   0
#define	APR_HOOK_MIDDLE   10
#define	APR_HOOK_LAST   20
#define	APR_HOOK_REALLY_LAST   30
Functions
void	apr_hook_sort_register (const char *szHookName, apr_array_header_t **aHooks)
void	apr_hook_sort_all (void)
void	apr_hook_debug_show (const char *szName, const char *const *aszPre, const char *const *aszSucc)
void	apr_hook_deregister_all (void)
Variables
apr_pool_t *	apr_hook_global_pool
int	apr_hook_debug_enabled
const char *	apr_hook_debug_current

---

Define Documentation

#define APR_DECLARE_EXTERNAL_HOOK	(	ns,
		link,
		ret,
		name,
		args		)

Value:

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 correctly

#define APR_HOOK_FIRST   0

run this hook first

#define APR_HOOK_LAST   20

run this hook after every other hook which is defined

#define APR_HOOK_LINK

(

name

)

apr_array_header_t *link_##name;

macro to link the hook structure

#define APR_HOOK_MIDDLE   10

run this hook somewhere

#define APR_HOOK_REALLY_FIRST   (-10)

run this hook first, before ANYTHING

#define APR_HOOK_REALLY_LAST   30

run this hook last, after EVERYTHING

#define APR_HOOK_STRUCT

(

members

)

static struct { members } _hooks;

macro to declare the hook structure

#define APR_IMPLEMENT_EXTERNAL_HOOK_BASE	(	ns,
		link,
		name		)

Value:

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; \
    }

macro to implement the hook

#define APR_IMPLEMENT_EXTERNAL_HOOK_RUN_ALL	(	ns,
		link,
		ret,
		name,
		args_decl,
		args_use,
		ok,
		decline		)

Value:

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; \
\
    if(!_hooks.link_##name) \
        return ok; \
\
    pHook=(ns##_LINK_##name##_t *)_hooks.link_##name->elts; \
    for(n=0 ; n < _hooks.link_##name->nelts ; ++n) \
        { \
        rv=pHook[n].pFunc args_use; \
\
        if(rv != ok && rv != decline) \
            return rv; \
        } \
    return ok; \
    }

Implement a hook that runs until one of the functions returns something other than OK or DECLINE

Parameters:

	ns	The namespace prefix of the hook functions
	link	The linkage declaration prefix of the hook
	ret	Type to return
	name	The name of the hook
	args_decl	The declaration of the arguments for the hook
	args_use	The names for the arguments for the hook
	ok	Success value
	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		)

Value:

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; \
\
    if(!_hooks.link_##name) \
        return decline; \
\
    pHook=(ns##_LINK_##name##_t *)_hooks.link_##name->elts; \
    for(n=0 ; n < _hooks.link_##name->nelts ; ++n) \
        { \
        rv=pHook[n].pFunc args_use; \
\
        if(rv != decline) \
            return rv; \
        } \
    return decline; \
    }

Implement a hook that runs until the first function returns something other than the value of decline

Parameters:

	ns	The namespace prefix of the hook functions
	link	The linkage declaration prefix of the hook
	name	The name of the hook
	ret	Type to return
	args_decl	The declaration of the arguments for the hook
	args_use	The names for the arguments for the hook
	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_VOID	(	ns,
		link,
		name,
		args_decl,
		args_use		)

Value:

APR_IMPLEMENT_EXTERNAL_HOOK_BASE(ns,link,name) \
link##_DECLARE(void) ns##_run_##name args_decl \
    { \
    ns##_LINK_##name##_t *pHook; \
    int n; \
\
    if(!_hooks.link_##name) \
        return; \
\
    pHook=(ns##_LINK_##name##_t *)_hooks.link_##name->elts; \
    for(n=0 ; n < _hooks.link_##name->nelts ; ++n) \
        pHook[n].pFunc args_use; \
    }

Implement a hook that has no return code, and therefore runs all of the registered functions

Parameters:

	ns	The namespace prefix of the hook functions
	link	The linkage declaration prefix of the hook
	name	The name of the hook
	args_decl	The declaration of the arguments for the hook
	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_HOOK_GET_PROTO	(	ns,
		link,
		name		)	link##_DECLARE(apr_array_header_t *) ns##_hook_get_##name(void)

macro to return the prototype of the hook function

---

Function Documentation

void apr_hook_debug_show	(	const char *	szName,
		const char *const *	aszPre,
		const char *const *	aszSucc
	)

Print all of the information about the current hook. This is used for debugging purposes.

Parameters:

	szName	The name of the hook
	aszPre	All of the functions in the predecessor array
	aszSucc	All of the functions in the successor array

void apr_hook_deregister_all

(

void

)

Remove all currently registered functions.

void apr_hook_sort_all

(

void

)

Sort all of the registerd functions for a given hook

void apr_hook_sort_register	(	const char *	szHookName,
		apr_array_header_t **	aHooks
	)

Register a hook function to be sorted

Parameters:

	szHookName	The name of the Hook the function is registered for
	aHooks	The array which stores all of the functions for this hook

---

Variable Documentation

const char* apr_hook_debug_current

The name of the module that is currently registering a function

int apr_hook_debug_enabled

A global variable to determine if debugging information about the hooks functions should be printed

apr_pool_t* apr_hook_global_pool

The global pool used to allocate any memory needed by the hooks.