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 /** @} */