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root/svn/ircd-hybrid/branches/8.1.x/src/hook.c
Revision: 2693
Committed: Tue Dec 17 19:35:26 2013 UTC (10 years, 3 months ago) by michael
Content type: text/x-csrc
File size: 5778 byte(s)
Log Message:
- Avoid magically sized temporary buffers

File Contents

# 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) 2005-2013 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;
41
42
43 /*! \brief Creates a new callback.
44 * \param name name used to identify the callback
45 * (can be NULL for anonymous callbacks)
46 * \param func initial function attached to the chain
47 * (can be NULL to create an empty chain)
48 * \return pointer to Callback structure or NULL if already exists
49 * \note Once registered, a callback should never be freed!
50 * That's because there may be modules which depend on it
51 * (even if no functions are attached). That's also why
52 * we dynamically allocate the struct here -- we don't want
53 * to allow anyone to place it in module data, which can be
54 * unloaded at any time.
55 */
56 struct Callback *
57 register_callback(const char *name, CBFUNC *func)
58 {
59 struct Callback *cb = NULL;
60
61 if (name != NULL)
62 {
63 if ((cb = find_callback(name)) != NULL)
64 {
65 if (func != NULL)
66 dlinkAddTail(func, MyMalloc(sizeof(dlink_node)), &cb->chain);
67
68 return cb;
69 }
70 }
71
72 cb = MyMalloc(sizeof(struct Callback));
73
74 if (func != NULL)
75 dlinkAdd(func, MyMalloc(sizeof(dlink_node)), &cb->chain);
76
77 if (name != NULL)
78 {
79 cb->name = xstrdup(name);
80 dlinkAdd(cb, &cb->node, &callback_list);
81 }
82
83 return cb;
84 }
85
86 /*! \brief Passes control down the callback hook chain.
87 * \param cb pointer to Callback structure
88 * \param ... argument to pass
89 * \return function return value
90 */
91 void *
92 execute_callback(struct Callback *cb, ...)
93 {
94 void *res = NULL;
95 va_list args;
96
97 cb->called++;
98 cb->last = CurrentTime;
99
100 if (!is_callback_present(cb))
101 return NULL;
102
103 va_start(args, cb);
104 res = ((CBFUNC *)cb->chain.head->data)(args);
105 va_end(args);
106
107 return res;
108 }
109
110 /*! \brief Called by a hook function to pass code flow further
111 * in the hook chain.
112 * \param this_hook pointer to dlink_node of the current hook function
113 * \param ... (original or modified) arguments to be passed
114 * \return callback return value
115 */
116 void *
117 pass_callback(dlink_node *this_hook, ...)
118 {
119 void *res = NULL;
120 va_list args;
121
122 if (this_hook->next == NULL)
123 return NULL; /* reached the last one */
124
125 va_start(args, this_hook);
126 res = ((CBFUNC *)this_hook->next->data)(args);
127 va_end(args);
128
129 return res;
130 }
131
132 /*! \brief Finds a named callback.
133 * \param name name of the callback
134 * \return pointer to Callback structure or NULL if not found
135 */
136 struct Callback *
137 find_callback(const char *name)
138 {
139 dlink_node *ptr = NULL;
140
141 DLINK_FOREACH(ptr, callback_list.head)
142 {
143 struct Callback *cb = ptr->data;
144
145 if (!irccmp(cb->name, name))
146 return cb;
147 }
148
149 return NULL;
150 }
151
152 /*! \brief Installs a hook for the given callback.
153 *
154 * The new hook is installed at the beginning of the chain,
155 * so it has full control over functions installed earlier.
156 *
157 * \param cb pointer to Callback structure
158 * \param hook address of hook function
159 * \return pointer to dlink_node of the hook (used when passing
160 * control to the next hook in the chain);
161 * valid till uninstall_hook() is called
162 */
163 dlink_node *
164 install_hook(struct Callback *cb, CBFUNC *hook)
165 {
166 dlink_node *node = MyMalloc(sizeof(dlink_node));
167
168 dlinkAdd(hook, node, &cb->chain);
169 return node;
170 }
171
172 /*! \brief Removes a specific hook for the given callback.
173 * \param cb pointer to Callback structure
174 * \param hook address of hook function
175 */
176 void
177 uninstall_hook(struct Callback *cb, CBFUNC *hook)
178 {
179 /* Let it core if not found */
180 dlink_node *ptr = dlinkFind(&cb->chain, hook);
181
182 dlinkDelete(ptr, &cb->chain);
183 MyFree(ptr);
184 }
185
186 /*! \brief Displays registered callbacks and lengths of their hook chains.
187 * (This is the handler of /stats h)
188 * \param source_p pointer to struct Client
189 */
190 void
191 stats_hooks(struct Client *source_p)
192 {
193 char lastused[IRCD_BUFSIZE];
194 const dlink_node *ptr = NULL;
195
196 sendto_one(source_p, ":%s %d %s : %-20s %-20s Used Hooks", me.name,
197 RPL_STATSDEBUG, source_p->name, "Callback", "Last Execution");
198 sendto_one(source_p, ":%s %d %s : ------------------------------------"
199 "--------------------", me.name, RPL_STATSDEBUG, source_p->name);
200
201 DLINK_FOREACH(ptr, callback_list.head)
202 {
203 const struct Callback *cb = ptr->data;
204
205 if (cb->last != 0)
206 snprintf(lastused, sizeof(lastused), "%d seconds ago",
207 (int) (CurrentTime - cb->last));
208 else
209 strcpy(lastused, "NEVER");
210
211 sendto_one(source_p, ":%s %d %s : %-20s %-20s %-8u %d", me.name,
212 RPL_STATSDEBUG, source_p->name, cb->name, lastused, cb->called,
213 dlink_list_length(&cb->chain));
214 }
215 }

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svn:keywords Id Revision