8.1.x/src/hook.c

/*
 *  ircd-hybrid: an advanced Internet Relay Chat Daemon(ircd).
 *
 *  Copyright (C) 2003 Piotr Nizynski, Advanced IRC Services Project Team
 *  Copyright (C) 2005 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
 *
 *  $Id$
 */

/*! \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 = { NULL, NULL, 0} ;

/*! \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;
  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;
  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;

  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)
{
  dlink_node *ptr;
  char lastused[32];

  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)
  {
    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));
  }

  sendto_one(source_p, ":%s %d %s : ", me.name, RPL_STATSDEBUG,
             source_p->name);
}
Revision:	1867
Committed:	Thu Apr 25 18:01:53 2013 UTC (10 years, 11 months ago) by michael
Content type:	text/x-csrc
File size:	5831 byte(s)
Log Message:	- Create 8.1.x branch
#	Content
1	/*
2	* ircd-hybrid: an advanced Internet Relay Chat Daemon(ircd).
3	*
4	* Copyright (C) 2003 Piotr Nizynski, Advanced IRC Services Project Team
5	* Copyright (C) 2005 Hybrid Development Team
6	*
7	* This program is free software; you can redistribute it and/or modify
8	* it under the terms of the GNU General Public License as published by
9	* the Free Software Foundation; either version 2 of the License, or
10	* (at your option) any later version.
11	*
12	* This program is distributed in the hope that it will be useful,
13	* but WITHOUT ANY WARRANTY; without even the implied warranty of
14	* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
15	* GNU General Public License for more details.
16	*
17	* You should have received a copy of the GNU General Public License
18	* along with this program; if not, write to the Free Software
19	* Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307
20	* USA
21	*
22	* $Id$
23	*/
24
25	/*! \file hook.c
26	* \brief Provides a generic event hooking interface.
27	* \version $Id$
28	*/
29
30	#include "stdinc.h"
31	#include "list.h"
32	#include "hook.h"
33	#include "ircd.h"
34	#include "memory.h"
35	#include "numeric.h"
36	#include "irc_string.h"
37	#include "send.h"
38	#include "client.h"
39
40	static dlink_list callback_list = { NULL, NULL, 0} ;
41
42	/*! \brief Creates a new callback.
43	* \param name name used to identify the callback
44	* (can be NULL for anonymous callbacks)
45	* \param func initial function attached to the chain
46	* (can be NULL to create an empty chain)
47	* \return pointer to Callback structure or NULL if already exists
48	* \note Once registered, a callback should never be freed!
49	* That's because there may be modules which depend on it
50	* (even if no functions are attached). That's also why
51	* we dynamically allocate the struct here -- we don't want
52	* to allow anyone to place it in module data, which can be
53	* unloaded at any time.
54	*/
55	struct Callback *
56	register_callback(const char name, CBFUNC func)
57	{
58	struct Callback *cb = NULL;
59
60	if (name != NULL)
61	{
62	if ((cb = find_callback(name)) != NULL)
63	{
64	if (func != NULL)
65	dlinkAddTail(func, MyMalloc(sizeof(dlink_node)), &cb->chain);
66
67	return cb;
68	}
69	}
70
71	cb = MyMalloc(sizeof(struct Callback));
72	if (func != NULL)
73	dlinkAdd(func, MyMalloc(sizeof(dlink_node)), &cb->chain);
74
75	if (name != NULL)
76	{
77	cb->name = xstrdup(name);
78	dlinkAdd(cb, &cb->node, &callback_list);
79	}
80
81	return cb;
82	}
83
84	/*! \brief Passes control down the callback hook chain.
85	* \param cb pointer to Callback structure
86	* \param ... argument to pass
87	* \return function return value
88	*/
89	void *
90	execute_callback(struct Callback *cb, ...)
91	{
92	void *res;
93	va_list args;
94
95	cb->called++;
96	cb->last = CurrentTime;
97
98	if (!is_callback_present(cb))
99	return NULL;
100
101	va_start(args, cb);
102	res = ((CBFUNC *) cb->chain.head->data)(args);
103	va_end(args);
104
105	return res;
106	}
107
108	/*! \brief Called by a hook function to pass code flow further
109	* in the hook chain.
110	* \param this_hook pointer to dlink_node of the current hook function
111	* \param ... (original or modified) arguments to be passed
112	* \return callback return value
113	*/
114	void *
115	pass_callback(dlink_node *this_hook, ...)
116	{
117	void *res;
118	va_list args;
119
120	if (this_hook->next == NULL)
121	return NULL; /* reached the last one */
122
123	va_start(args, this_hook);
124	res = ((CBFUNC *) this_hook->next->data)(args);
125	va_end(args);
126
127	return res;
128	}
129
130	/*! \brief Finds a named callback.
131	* \param name name of the callback
132	* \return pointer to Callback structure or NULL if not found
133	*/
134	struct Callback *
135	find_callback(const char *name)
136	{
137	dlink_node *ptr;
138
139	DLINK_FOREACH(ptr, callback_list.head)
140	{
141	struct Callback *cb = ptr->data;
142
143	if (!irccmp(cb->name, name))
144	return cb;
145	}
146
147	return NULL;
148	}
149
150	/*! \brief Installs a hook for the given callback.
151	*
152	* The new hook is installed at the beginning of the chain,
153	* so it has full control over functions installed earlier.
154	*
155	* \param cb pointer to Callback structure
156	* \param hook address of hook function
157	* \return pointer to dlink_node of the hook (used when passing
158	* control to the next hook in the chain);
159	* valid till uninstall_hook() is called
160	*/
161	dlink_node *
162	install_hook(struct Callback cb, CBFUNC hook)
163	{
164	dlink_node *node = MyMalloc(sizeof(dlink_node));
165
166	dlinkAdd(hook, node, &cb->chain);
167	return node;
168	}
169
170	/*! \brief Removes a specific hook for the given callback.
171	* \param cb pointer to Callback structure
172	* \param hook address of hook function
173	*/
174	void
175	uninstall_hook(struct Callback cb, CBFUNC hook)
176	{
177	/* let it core if not found */
178	dlink_node *ptr = dlinkFind(&cb->chain, hook);
179
180	dlinkDelete(ptr, &cb->chain);
181	MyFree(ptr);
182	}
183
184	/*! \brief Displays registered callbacks and lengths of their hook chains.
185	* (This is the handler of /stats h)
186	* \param source_p pointer to struct Client
187	*/
188	void
189	stats_hooks(struct Client *source_p)
190	{
191	dlink_node *ptr;
192	char lastused[32];
193
194	sendto_one(source_p, ":%s %d %s : %-20s %-20s Used Hooks", me.name,
195	RPL_STATSDEBUG, source_p->name, "Callback", "Last Execution");
196	sendto_one(source_p, ":%s %d %s : ------------------------------------"
197	"--------------------", me.name, RPL_STATSDEBUG, source_p->name);
198
199	DLINK_FOREACH(ptr, callback_list.head)
200	{
201	struct Callback *cb = ptr->data;
202
203	if (cb->last != 0)
204	snprintf(lastused, sizeof(lastused), "%d seconds ago",
205	(int) (CurrentTime - cb->last));
206	else
207	strcpy(lastused, "NEVER");
208
209	sendto_one(source_p, ":%s %d %s : %-20s %-20s %-8u %d", me.name,
210	RPL_STATSDEBUG, source_p->name, cb->name, lastused, cb->called,
211	dlink_list_length(&cb->chain));
212	}
213
214	sendto_one(source_p, ":%s %d %s : ", me.name, RPL_STATSDEBUG,
215	source_p->name);
216	}