trunk/src/hook.c

/*
 *  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));
  }
}
Revision:	2846
Committed:	Fri Jan 17 16:58:36 2014 UTC (11 years, 7 months ago) by michael
Content type:	text/x-csrc
File size:	5785 byte(s)
Log Message:	- hook.h, hook.c: fixed indentation, removed whitespaces/tabs
#	Content
1	/*
2	* ircd-hybrid: an advanced, lightweight Internet Relay Chat Daemon (ircd)
3	*
4	* Copyright (c) 2003 Piotr Nizynski, Advanced IRC Services Project Team
5	* Copyright (c) 2005-2014 ircd-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
23	/*! \file hook.c
24	* \brief Provides a generic event hooking interface.
25	* \version $Id$
26	*/
27
28	#include "stdinc.h"
29	#include "list.h"
30	#include "hook.h"
31	#include "ircd.h"
32	#include "memory.h"
33	#include "numeric.h"
34	#include "irc_string.h"
35	#include "send.h"
36	#include "client.h"
37
38
39	static dlink_list callback_list;
40
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
73	if (func != NULL)
74	dlinkAdd(func, MyMalloc(sizeof(dlink_node)), &cb->chain);
75
76	if (name != NULL)
77	{
78	cb->name = xstrdup(name);
79	dlinkAdd(cb, &cb->node, &callback_list);
80	}
81
82	return cb;
83	}
84
85	/*! \brief Passes control down the callback hook chain.
86	* \param cb Pointer to Callback structure
87	* \param ... Argument to pass
88	* \return function Return value
89	*/
90	void *
91	execute_callback(struct Callback *cb, ...)
92	{
93	void *res = NULL;
94	va_list args;
95
96	cb->called++;
97	cb->last = CurrentTime;
98
99	if (!is_callback_present(cb))
100	return NULL;
101
102	va_start(args, cb);
103	res = ((CBFUNC *)cb->chain.head->data)(args);
104	va_end(args);
105
106	return res;
107	}
108
109	/*! \brief Called by a hook function to pass code flow further
110	* in the hook chain.
111	* \param this_hook Pointer to dlink_node of the current hook function
112	* \param ... (original or modified) arguments to be passed
113	* \return callback Return value
114	*/
115	void *
116	pass_callback(dlink_node *this_hook, ...)
117	{
118	void *res = NULL;
119	va_list args;
120
121	if (this_hook->next == NULL)
122	return NULL; /* Reached the last one */
123
124	va_start(args, this_hook);
125	res = ((CBFUNC *)this_hook->next->data)(args);
126	va_end(args);
127
128	return res;
129	}
130
131	/*! \brief Finds a named callback.
132	* \param name Name of the callback
133	* \return Pointer to Callback structure or NULL if not found
134	*/
135	struct Callback *
136	find_callback(const char *name)
137	{
138	dlink_node *ptr = NULL;
139
140	DLINK_FOREACH(ptr, callback_list.head)
141	{
142	struct Callback *cb = ptr->data;
143
144	if (!irccmp(cb->name, name))
145	return cb;
146	}
147
148	return NULL;
149	}
150
151	/*! \brief Installs a hook for the given callback.
152	*
153	* The new hook is installed at the beginning of the chain,
154	* so it has full control over functions installed earlier.
155	*
156	* \param cb Pointer to Callback structure
157	* \param hook Address of hook function
158	* \return Pointer to dlink_node of the hook (used when passing
159	* control to the next hook in the chain);
160	* valid till uninstall_hook() is called
161	*/
162	dlink_node *
163	install_hook(struct Callback cb, CBFUNC hook)
164	{
165	dlink_node *node = MyMalloc(sizeof(dlink_node));
166
167	dlinkAdd(hook, node, &cb->chain);
168	return node;
169	}
170
171	/*! \brief Removes a specific hook for the given callback.
172	* \param cb Pointer to Callback structure
173	* \param hook Address of hook function
174	*/
175	void
176	uninstall_hook(struct Callback cb, CBFUNC hook)
177	{
178	/* Let it core if not found */
179	dlink_node *ptr = dlinkFind(&cb->chain, hook);
180
181	dlinkDelete(ptr, &cb->chain);
182	MyFree(ptr);
183	}
184
185	/*! \brief Displays registered callbacks and lengths of their hook chains.
186	* (This is the handler of /stats h)
187	* \param source_p Pointer to struct Client
188	*/
189	void
190	stats_hooks(struct Client *source_p)
191	{
192	char lastused[IRCD_BUFSIZE];
193	const dlink_node *ptr = NULL;
194
195	sendto_one(source_p, ":%s %d %s : %-20s %-20s Used Hooks", me.name,
196	RPL_STATSDEBUG, source_p->name, "Callback", "Last Execution");
197	sendto_one(source_p, ":%s %d %s : ------------------------------------"
198	"--------------------", me.name, RPL_STATSDEBUG, source_p->name);
199
200	DLINK_FOREACH(ptr, callback_list.head)
201	{
202	const struct Callback *cb = ptr->data;
203
204	if (cb->last != 0)
205	snprintf(lastused, sizeof(lastused), "%d seconds ago",
206	(int) (CurrentTime - cb->last));
207	else
208	strcpy(lastused, "NEVER");
209
210	sendto_one(source_p, ":%s %d %s : %-20s %-20s %-8u %d", me.name,
211	RPL_STATSDEBUG, source_p->name, cb->name, lastused, cb->called,
212	dlink_list_length(&cb->chain));
213	}
214	}