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/*
* ircd-hybrid: an advanced, lightweight Internet Relay Chat Daemon (ircd)
*
* Copyright (c) 2003 Piotr Nizynski, Advanced IRC Services Project Team
* Copyright (c) 2005-2014 ircd-hybrid development team
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation; either version 2 of the License, or
* (at your option) any later version.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program; if not, write to the Free Software
* Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307
* USA
*/
/*! \file hook.c
* \brief Provides a generic event hooking interface.
* \version $Id$
*/
#include "stdinc.h"
#include "list.h"
#include "hook.h"
#include "ircd.h"
#include "memory.h"
#include "numeric.h"
#include "irc_string.h"
#include "send.h"
#include "client.h"
static dlink_list callback_list;
/*! \brief Creates a new callback.
* \param name Name used to identify the callback
* (can be NULL for anonymous callbacks)
* \param func Initial function attached to the chain
* (can be NULL to create an empty chain)
* \return Pointer to Callback structure or NULL if already exists
* \note Once registered, a callback should never be freed!
* That's because there may be modules which depend on it
* (even if no functions are attached). That's also why
* we dynamically allocate the struct here -- we don't want
* to allow anyone to place it in module data, which can be
* unloaded at any time.
*/
struct Callback *
register_callback(const char *name, CBFUNC *func)
{
struct Callback *cb = NULL;
if (name != NULL)
{
if ((cb = find_callback(name)) != NULL)
{
if (func != NULL)
dlinkAddTail(func, MyMalloc(sizeof(dlink_node)), &cb->chain);
return cb;
}
}
cb = MyMalloc(sizeof(struct Callback));
if (func != NULL)
dlinkAdd(func, MyMalloc(sizeof(dlink_node)), &cb->chain);
if (name != NULL)
{
cb->name = xstrdup(name);
dlinkAdd(cb, &cb->node, &callback_list);
}
return cb;
}
/*! \brief Passes control down the callback hook chain.
* \param cb Pointer to Callback structure
* \param ... Argument to pass
* \return function Return value
*/
void *
execute_callback(struct Callback *cb, ...)
{
void *res = NULL;
va_list args;
cb->called++;
cb->last = CurrentTime;
if (!is_callback_present(cb))
return NULL;
va_start(args, cb);
res = ((CBFUNC *)cb->chain.head->data)(args);
va_end(args);
return res;
}
/*! \brief Called by a hook function to pass code flow further
* in the hook chain.
* \param this_hook Pointer to dlink_node of the current hook function
* \param ... (original or modified) arguments to be passed
* \return callback Return value
*/
void *
pass_callback(dlink_node *this_hook, ...)
{
void *res = NULL;
va_list args;
if (this_hook->next == NULL)
return NULL; /* Reached the last one */
va_start(args, this_hook);
res = ((CBFUNC *)this_hook->next->data)(args);
va_end(args);
return res;
}
/*! \brief Finds a named callback.
* \param name Name of the callback
* \return Pointer to Callback structure or NULL if not found
*/
struct Callback *
find_callback(const char *name)
{
dlink_node *ptr = NULL;
DLINK_FOREACH(ptr, callback_list.head)
{
struct Callback *cb = ptr->data;
if (!irccmp(cb->name, name))
return cb;
}
return NULL;
}
/*! \brief Installs a hook for the given callback.
*
* The new hook is installed at the beginning of the chain,
* so it has full control over functions installed earlier.
*
* \param cb Pointer to Callback structure
* \param hook Address of hook function
* \return Pointer to dlink_node of the hook (used when passing
* control to the next hook in the chain);
* valid till uninstall_hook() is called
*/
dlink_node *
install_hook(struct Callback *cb, CBFUNC *hook)
{
dlink_node *node = MyMalloc(sizeof(dlink_node));
dlinkAdd(hook, node, &cb->chain);
return node;
}
/*! \brief Removes a specific hook for the given callback.
* \param cb Pointer to Callback structure
* \param hook Address of hook function
*/
void
uninstall_hook(struct Callback *cb, CBFUNC *hook)
{
/* Let it core if not found */
dlink_node *ptr = dlinkFind(&cb->chain, hook);
dlinkDelete(ptr, &cb->chain);
MyFree(ptr);
}
/*! \brief Displays registered callbacks and lengths of their hook chains.
* (This is the handler of /stats h)
* \param source_p Pointer to struct Client
*/
void
stats_hooks(struct Client *source_p)
{
char lastused[IRCD_BUFSIZE];
const dlink_node *ptr = NULL;
sendto_one(source_p, ":%s %d %s : %-20s %-20s Used Hooks", me.name,
RPL_STATSDEBUG, source_p->name, "Callback", "Last Execution");
sendto_one(source_p, ":%s %d %s : ------------------------------------"
"--------------------", me.name, RPL_STATSDEBUG, source_p->name);
DLINK_FOREACH(ptr, callback_list.head)
{
const struct Callback *cb = ptr->data;
if (cb->last != 0)
snprintf(lastused, sizeof(lastused), "%d seconds ago",
(int) (CurrentTime - cb->last));
else
strcpy(lastused, "NEVER");
sendto_one(source_p, ":%s %d %s : %-20s %-20s %-8u %d", me.name,
RPL_STATSDEBUG, source_p->name, cb->name, lastused, cb->called,
dlink_list_length(&cb->chain));
}
}
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