add libnl-tiny as a small replacement for libnl with only genl support included
[openwrt/svn-archive/archive.git] / package / libnl-tiny / src / cache_mngt.c
1 /*
2 * lib/cache_mngt.c Cache Management
3 *
4 * This library is free software; you can redistribute it and/or
5 * modify it under the terms of the GNU Lesser General Public
6 * License as published by the Free Software Foundation version 2.1
7 * of the License.
8 *
9 * Copyright (c) 2003-2008 Thomas Graf <tgraf@suug.ch>
10 */
11
12 /**
13 * @ingroup core
14 * @defgroup cache_mngt Caching
15 * @{
16 */
17
18 #include <netlink-local.h>
19 #include <netlink/netlink.h>
20 #include <netlink/cache.h>
21 #include <netlink/utils.h>
22
23 static struct nl_cache_ops *cache_ops;
24
25 /**
26 * @name Cache Operations Sets
27 * @{
28 */
29
30 /**
31 * Lookup the set cache operations of a certain cache type
32 * @arg name name of the cache type
33 *
34 * @return The cache operations or NULL if no operations
35 * have been registered under the specified name.
36 */
37 struct nl_cache_ops *nl_cache_ops_lookup(const char *name)
38 {
39 struct nl_cache_ops *ops;
40
41 for (ops = cache_ops; ops; ops = ops->co_next)
42 if (!strcmp(ops->co_name, name))
43 return ops;
44
45 return NULL;
46 }
47
48 /**
49 * Associate a message type to a set of cache operations
50 * @arg protocol netlink protocol
51 * @arg msgtype netlink message type
52 *
53 * Associates the specified netlink message type with
54 * a registered set of cache operations.
55 *
56 * @return The cache operations or NULL if no association
57 * could be made.
58 */
59 struct nl_cache_ops *nl_cache_ops_associate(int protocol, int msgtype)
60 {
61 int i;
62 struct nl_cache_ops *ops;
63
64 for (ops = cache_ops; ops; ops = ops->co_next) {
65 if (ops->co_protocol != protocol)
66 continue;
67
68 for (i = 0; ops->co_msgtypes[i].mt_id >= 0; i++)
69 if (ops->co_msgtypes[i].mt_id == msgtype)
70 return ops;
71 }
72
73 return NULL;
74 }
75
76 /**
77 * Lookup message type cache association
78 * @arg ops cache operations
79 * @arg msgtype netlink message type
80 *
81 * Searches for a matching message type association ing the specified
82 * cache operations.
83 *
84 * @return A message type association or NULL.
85 */
86 struct nl_msgtype *nl_msgtype_lookup(struct nl_cache_ops *ops, int msgtype)
87 {
88 int i;
89
90 for (i = 0; ops->co_msgtypes[i].mt_id >= 0; i++)
91 if (ops->co_msgtypes[i].mt_id == msgtype)
92 return &ops->co_msgtypes[i];
93
94 return NULL;
95 }
96
97 static struct nl_cache_ops *cache_ops_lookup_for_obj(struct nl_object_ops *obj_ops)
98 {
99 struct nl_cache_ops *ops;
100
101 for (ops = cache_ops; ops; ops = ops->co_next)
102 if (ops->co_obj_ops == obj_ops)
103 return ops;
104
105 return NULL;
106
107 }
108
109 /**
110 * Call a function for each registered cache operation
111 * @arg cb Callback function to be called
112 * @arg arg User specific argument.
113 */
114 void nl_cache_ops_foreach(void (*cb)(struct nl_cache_ops *, void *), void *arg)
115 {
116 struct nl_cache_ops *ops;
117
118 for (ops = cache_ops; ops; ops = ops->co_next)
119 cb(ops, arg);
120 }
121
122 /**
123 * Register a set of cache operations
124 * @arg ops cache operations
125 *
126 * Called by users of caches to announce the avaibility of
127 * a certain cache type.
128 *
129 * @return 0 on success or a negative error code.
130 */
131 int nl_cache_mngt_register(struct nl_cache_ops *ops)
132 {
133 if (!ops->co_name || !ops->co_obj_ops)
134 return -NLE_INVAL;
135
136 if (nl_cache_ops_lookup(ops->co_name))
137 return -NLE_EXIST;
138
139 ops->co_next = cache_ops;
140 cache_ops = ops;
141
142 NL_DBG(1, "Registered cache operations %s\n", ops->co_name);
143
144 return 0;
145 }
146
147 /**
148 * Unregister a set of cache operations
149 * @arg ops cache operations
150 *
151 * Called by users of caches to announce a set of
152 * cache operations is no longer available. The
153 * specified cache operations must have been registered
154 * previously using nl_cache_mngt_register()
155 *
156 * @return 0 on success or a negative error code
157 */
158 int nl_cache_mngt_unregister(struct nl_cache_ops *ops)
159 {
160 struct nl_cache_ops *t, **tp;
161
162 for (tp = &cache_ops; (t=*tp) != NULL; tp = &t->co_next)
163 if (t == ops)
164 break;
165
166 if (!t)
167 return -NLE_NOCACHE;
168
169 NL_DBG(1, "Unregistered cache operations %s\n", ops->co_name);
170
171 *tp = t->co_next;
172 return 0;
173 }
174
175 /** @} */
176
177 /**
178 * @name Global Cache Provisioning/Requiring
179 * @{
180 */
181
182 /**
183 * Provide a cache for global use
184 * @arg cache cache to provide
185 *
186 * Offers the specified cache to be used by other modules.
187 * Only one cache per type may be shared at a time,
188 * a previsouly provided caches will be overwritten.
189 */
190 void nl_cache_mngt_provide(struct nl_cache *cache)
191 {
192 struct nl_cache_ops *ops;
193
194 ops = cache_ops_lookup_for_obj(cache->c_ops->co_obj_ops);
195 if (!ops)
196 BUG();
197 else
198 ops->co_major_cache = cache;
199 }
200
201 /**
202 * Unprovide a cache for global use
203 * @arg cache cache to unprovide
204 *
205 * Cancels the offer to use a cache globally. The
206 * cache will no longer be returned via lookups but
207 * may still be in use.
208 */
209 void nl_cache_mngt_unprovide(struct nl_cache *cache)
210 {
211 struct nl_cache_ops *ops;
212
213 ops = cache_ops_lookup_for_obj(cache->c_ops->co_obj_ops);
214 if (!ops)
215 BUG();
216 else if (ops->co_major_cache == cache)
217 ops->co_major_cache = NULL;
218 }
219
220 /**
221 * Demand the use of a global cache
222 * @arg name name of the required object type
223 *
224 * Trys to find a cache of the specified type for global
225 * use.
226 *
227 * @return A cache provided by another subsystem of the
228 * specified type marked to be available.
229 */
230 struct nl_cache *nl_cache_mngt_require(const char *name)
231 {
232 struct nl_cache_ops *ops;
233
234 ops = nl_cache_ops_lookup(name);
235 if (!ops || !ops->co_major_cache) {
236 fprintf(stderr, "Application BUG: Your application must "
237 "call nl_cache_mngt_provide() and\nprovide a valid "
238 "%s cache to be used for internal lookups.\nSee the "
239 " API documentation for more details.\n", name);
240
241 return NULL;
242 }
243
244 return ops->co_major_cache;
245 }
246
247 /** @} */
248
249 /** @} */