libio/misc/hook.c

/*
 *  ircd-hybrid: an advanced Internet Relay Chat Daemon(ircd).
 *  hook.c: Provides a generic event hooking interface.
 *
 *  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: hook.c 33 2005-10-02 20:50:00Z knight $
 */

#include "stdinc.h"
#include "client.h"
#include "hook.h"
#include "ircd.h"
#include "list.h"
#include "memory.h"
#include "numeric.h"
#include "tools.h"
#include "irc_string.h"
#include "send.h"

dlink_list callback_list = {NULL, NULL, 0};

/*
 * register_callback()
 *
 * Creates a new callback.
 *
 * inputs:
 *   name  -  name used to identify the callback
 *            (can be NULL for anonymous callbacks)
 *   func  -  initial function attached to the chain
 *            (can be NULL to create an empty chain)
 * output: 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;

  if (name != NULL)
    if ((cb = find_callback(name)) != NULL)
    {
      /* re-attaching an empty hook chain? */
      if (!is_callback_present(cb))
      {
        dlinkAdd(func, MyMalloc(sizeof(dlink_node)), &cb->chain);
        return (cb);
      }
      return (NULL);
    }

  cb = MyMalloc(sizeof(struct Callback));
  if (func != NULL)
    dlinkAdd(func, MyMalloc(sizeof(dlink_node)), &cb->chain);
  if (name != NULL)
  {
    DupString(cb->name, name);
    dlinkAdd(cb, &cb->node, &callback_list);
  }
  return (cb);
}

/*
 * execute_callback()
 *
 * Passes control down the callback hook chain.
 *
 * inputs:
 *   callback  -  pointer to Callback structure
 *   param     -  argument to pass
 * output: 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);
}

/*
 * pass_callback()
 *
 * Called by a hook function to pass code flow further
 * in the hook chain.
 *
 * inputs:
 *   this_hook  -  pointer to dlink_node of the current hook function
 *   ...        -  (original or modified) arguments to be passed
 * output: 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);
}

/*
 * find_callback()
 *
 * Finds a named callback.
 *
 * inputs:
 *   name  -  name of the callback
 * output: pointer to Callback structure or NULL if not found
 */
struct Callback *
find_callback(const char *name)
{
  struct Callback *cb;
  dlink_node *ptr;

  DLINK_FOREACH(ptr, callback_list.head)
  {
    cb = ptr->data;
    if (!irccmp(cb->name, name))
      return (cb);
  }

  return (NULL);
}

/*
 * install_hook()
 *
 * Installs a hook for the given callback.
 *
 * inputs:
 *   cb      -  pointer to Callback structure
 *   hook    -  address of hook function
 * output: pointer to dlink_node of the hook (used when
 *         passing control to the next hook in the chain);
 *         valid till uninstall_hook() is called
 *
 * NOTE: The new hook is installed at the beginning of the chain,
 * so it has full control over functions installed earlier.
 */
dlink_node *
install_hook(struct Callback *cb, CBFUNC *hook)
{
  dlink_node *node = MyMalloc(sizeof(dlink_node));

  dlinkAdd(hook, node, &cb->chain);
  return (node);
}

/*
 * uninstall_hook()
 *
 * Removes a specific hook for the given callback.
 *
 * inputs:
 *   cb      -  pointer to Callback structure
 *   hook    -  address of hook function
 * output: none
 */
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);
}

/*
 * stats_hooks()
 *
 * Displays registered callbacks and lengths of their hook chains.
 * (This is the handler of /stats h)
 *
 * inputs:
 *   source_p  -  pointer to struct Client
 * output: none
 */
void
stats_hooks(struct Client *source_p)
{
  dlink_node *ptr;
  struct Callback *cb;
  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)
  {
    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:	62
Committed:	Mon Oct 3 22:23:39 2005 UTC (20 years, 10 months ago) by adx
Content type:	text/x-csrc
File size:	6190 byte(s)
Log Message:	- reorganisation goes on, removed external references from libio/mem
#	User	Rev	Content
1	adx	61	/*
2			* ircd-hybrid: an advanced Internet Relay Chat Daemon(ircd).
3			* hook.c: Provides a generic event hooking interface.
4			*
5			* Copyright (C) 2003 Piotr Nizynski, Advanced IRC Services Project Team
6			* Copyright (C) 2005 Hybrid Development Team
7			*
8			* This program is free software; you can redistribute it and/or modify
9			* it under the terms of the GNU General Public License as published by
10			* the Free Software Foundation; either version 2 of the License, or
11			* (at your option) any later version.
12			*
13			* This program is distributed in the hope that it will be useful,
14			* but WITHOUT ANY WARRANTY; without even the implied warranty of
15			* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
16			* GNU General Public License for more details.
17			*
18			* You should have received a copy of the GNU General Public License
19			* along with this program; if not, write to the Free Software
20			* Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307
21			* USA
22			*
23			* $Id: hook.c 33 2005-10-02 20:50:00Z knight $
24			*/
25
26			#include "stdinc.h"
27	adx	62	#include "client.h"
28	adx	61	#include "hook.h"
29			#include "ircd.h"
30			#include "list.h"
31			#include "memory.h"
32			#include "numeric.h"
33			#include "tools.h"
34			#include "irc_string.h"
35			#include "send.h"
36
37			dlink_list callback_list = {NULL, NULL, 0};
38
39			/*
40			* register_callback()
41			*
42			* Creates a new callback.
43			*
44			* inputs:
45			* name - name used to identify the callback
46			* (can be NULL for anonymous callbacks)
47			* func - initial function attached to the chain
48			* (can be NULL to create an empty chain)
49			* output: pointer to Callback structure or NULL if already exists
50			*
51			* NOTE: Once registered, a callback should never be freed!
52			* That's because there may be modules which depend on it
53			* (even if no functions are attached). That's also why
54			* we dynamically allocate the struct here -- we don't want
55			* to allow anyone to place it in module data, which can be
56			* unloaded at any time.
57			*/
58			struct Callback *
59			register_callback(const char name, CBFUNC func)
60			{
61			struct Callback *cb;
62
63			if (name != NULL)
64			if ((cb = find_callback(name)) != NULL)
65			{
66			/* re-attaching an empty hook chain? */
67			if (!is_callback_present(cb))
68			{
69			dlinkAdd(func, MyMalloc(sizeof(dlink_node)), &cb->chain);
70			return (cb);
71			}
72			return (NULL);
73			}
74
75			cb = MyMalloc(sizeof(struct Callback));
76			if (func != NULL)
77			dlinkAdd(func, MyMalloc(sizeof(dlink_node)), &cb->chain);
78			if (name != NULL)
79			{
80			DupString(cb->name, name);
81			dlinkAdd(cb, &cb->node, &callback_list);
82			}
83			return (cb);
84			}
85
86			/*
87			* execute_callback()
88			*
89			* Passes control down the callback hook chain.
90			*
91			* inputs:
92			* callback - pointer to Callback structure
93			* param - argument to pass
94			* output: function return value
95			*/
96			void *
97			execute_callback(struct Callback *cb, ...)
98			{
99			void *res;
100			va_list args;
101
102			cb->called++;
103			cb->last = CurrentTime;
104
105			if (!is_callback_present(cb))
106			return (NULL);
107
108			va_start(args, cb);
109			res = ((CBFUNC *) cb->chain.head->data)(args);
110			va_end(args);
111			return (res);
112			}
113
114			/*
115			* pass_callback()
116			*
117			* Called by a hook function to pass code flow further
118			* in the hook chain.
119			*
120			* inputs:
121			* this_hook - pointer to dlink_node of the current hook function
122			* ... - (original or modified) arguments to be passed
123			* output: callback return value
124			*/
125			void *
126			pass_callback(dlink_node *this_hook, ...)
127			{
128			void *res;
129			va_list args;
130
131			if (this_hook->next == NULL)
132			return (NULL); /* reached the last one */
133
134			va_start(args, this_hook);
135			res = ((CBFUNC *) this_hook->next->data)(args);
136			va_end(args);
137			return (res);
138			}
139
140			/*
141			* find_callback()
142			*
143			* Finds a named callback.
144			*
145			* inputs:
146			* name - name of the callback
147			* output: pointer to Callback structure or NULL if not found
148			*/
149			struct Callback *
150			find_callback(const char *name)
151			{
152			struct Callback *cb;
153			dlink_node *ptr;
154
155			DLINK_FOREACH(ptr, callback_list.head)
156			{
157			cb = ptr->data;
158			if (!irccmp(cb->name, name))
159			return (cb);
160			}
161
162			return (NULL);
163			}
164
165			/*
166			* install_hook()
167			*
168			* Installs a hook for the given callback.
169			*
170			* inputs:
171			* cb - pointer to Callback structure
172			* hook - address of hook function
173			* output: pointer to dlink_node of the hook (used when
174			* passing control to the next hook in the chain);
175			* valid till uninstall_hook() is called
176			*
177			* NOTE: The new hook is installed at the beginning of the chain,
178			* so it has full control over functions installed earlier.
179			*/
180			dlink_node *
181			install_hook(struct Callback cb, CBFUNC hook)
182			{
183			dlink_node *node = MyMalloc(sizeof(dlink_node));
184
185			dlinkAdd(hook, node, &cb->chain);
186			return (node);
187			}
188
189			/*
190			* uninstall_hook()
191			*
192			* Removes a specific hook for the given callback.
193			*
194			* inputs:
195			* cb - pointer to Callback structure
196			* hook - address of hook function
197			* output: none
198			*/
199			void
200			uninstall_hook(struct Callback cb, CBFUNC hook)
201			{
202			/* let it core if not found */
203			dlink_node *ptr = dlinkFind(&cb->chain, hook);
204
205			dlinkDelete(ptr, &cb->chain);
206			MyFree(ptr);
207			}
208
209			/*
210			* stats_hooks()
211			*
212			* Displays registered callbacks and lengths of their hook chains.
213			* (This is the handler of /stats h)
214			*
215			* inputs:
216			* source_p - pointer to struct Client
217			* output: none
218			*/
219			void
220			stats_hooks(struct Client *source_p)
221			{
222			dlink_node *ptr;
223			struct Callback *cb;
224			char lastused[32];
225
226			sendto_one(source_p, ":%s %d %s : %-20s %-20s Used Hooks", me.name,
227			RPL_STATSDEBUG, source_p->name, "Callback", "Last Execution");
228			sendto_one(source_p, ":%s %d %s : ------------------------------------"
229			"--------------------", me.name, RPL_STATSDEBUG, source_p->name);
230
231			DLINK_FOREACH(ptr, callback_list.head)
232			{
233			cb = ptr->data;
234
235			if (cb->last != 0)
236			snprintf(lastused, sizeof(lastused), "%d seconds ago",
237			(int) (CurrentTime - cb->last));
238			else
239			strcpy(lastused, "NEVER");
240
241			sendto_one(source_p, ":%s %d %s : %-20s %-20s %-8u %d", me.name,
242			RPL_STATSDEBUG, source_p->name, cb->name, lastused, cb->called,
243			dlink_list_length(&cb->chain));
244			}
245
246			sendto_one(source_p, ":%s %d %s : ", me.name, RPL_STATSDEBUG,
247			source_p->name);
248			}