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cache.c

/*
 * lib/cache.c          Caching Module
 *
 *          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.
 *
 * Copyright (c) 2003-2005 Thomas Graf <tgraf@suug.ch>
 */

/**
 * @ingroup utils
 * @defgroup cache Caching
 *
 * @code
 *   Cache Management             |    | Type Specific Cache Operations
 *                                      
 *                                |    | +----------------+ +------------+
 *                                       | request update | | msg_parser |
 *                                |    | +----------------+ +------------+
 *                                     +- - - - -^- - - - - - - -^- -|- - - -
 *    nl_cache_update:            |              |               |   |
 *          1) --------- co_request_update ------+               |   |
 *                                |                              |   |
 *          2) destroy old cache     +----------- pp_cb ---------|---+
 *                                |  |                           |
 *          3) ---------- nl_recvmsgs ----------+   +- cb_valid -+
 *             +--------------+   |  |          |   |
 *             | nl_cache_add |<-----+   + - - -v- -|- - - - - - - - - - -
 *             +--------------+   |      | +-------------+
 *                                         | nl_recvmsgs |
 *                                |      | +-----|-^-----+
 *                                           +---v-|---+
 *                                |      |   | nl_recv |
 *                                           +---------+
 *                                |      |                 Core Netlink
 * @endcode
 * 
 * @{
 */

#include <netlink-local.h>
#include <netlink/netlink.h>
#include <netlink/cache.h>
#include <netlink/object.h>
#include <netlink/utils.h>

/**
 * @name Access Functions
 * @{
 */

/**
 * Return the number of items in the cache
 * @arg cache           cache handle
 */
00058 int nl_cache_nitems(struct nl_cache *cache)
{
      return cache->c_nitems;
}

/**
 * Return the number of items matching a filter in the cache
 * @arg cache           Cache object.
 * @arg filter          Filter object.
 */
00068 int nl_cache_nitems_filter(struct nl_cache *cache, struct nl_object *filter)
{
      struct nl_cache_ops *ops = cache->c_ops;
      struct nl_object *obj;
      int nitems = 0;
      
      nl_list_for_each_entry(obj, &cache->c_items, ce_list) {
            if (filter && ops->co_filter && !ops->co_filter(obj, filter))
                  continue;

            nitems++;
      }

      return nitems;
}

/**
 * Returns \b true if the cache is empty.
 * @arg cache           Cache to check
 * @return \a true if the cache is empty, otherwise \b false is returned.
 */
00089 inline int nl_cache_is_empty(struct nl_cache *cache)
{
      return nl_list_empty(&cache->c_items);
}

/**
 * Return the operations set of the cache
 * @arg cache           cache handle
 */
00098 struct nl_cache_ops *nl_cache_get_ops(struct nl_cache *cache)
{
      return cache->c_ops;
}

/**
 * Return the first element in the cache
 * @arg cache           cache handle
 */
00107 struct nl_object *nl_cache_get_first(struct nl_cache *cache)
{
      if (nl_list_empty(&cache->c_items))
            return NULL;

      return nl_list_entry(cache->c_items.next,
                       struct nl_object, ce_list);
}

/**
 * Return the last element in the cache
 * @arg cache           cache handle
 */
00120 struct nl_object *nl_cache_get_last(struct nl_cache *cache)
{
      if (nl_list_empty(&cache->c_items))
            return NULL;

      return nl_list_entry(cache->c_items.prev,
                       struct nl_object, ce_list);
}

/**
 * Return the next element in the cache
 * @arg obj       current object
 */
00133 struct nl_object *nl_cache_get_next(struct nl_object *obj)
{
      if (nl_list_at_tail(obj, &obj->ce_cache->c_items, ce_list))
            return NULL;
      else
            return nl_list_entry(obj->ce_list.next,
                             struct nl_object, ce_list);
}

/**
 * Return the previous element in the cache
 * @arg obj       current object
 */
00146 struct nl_object *nl_cache_get_prev(struct nl_object *obj)
{
      if (nl_list_at_head(obj, &obj->ce_cache->c_items, ce_list))
            return NULL;
      else
            return nl_list_entry(obj->ce_list.prev,
                             struct nl_object, ce_list);
}

/** @} */

/**
 * @name Cache Creation/Deletion
 * @{
 */

/**
 * Allocate an empty cache of no certain type
 * 
 * @return A newly allocated and initialized cache.
 */
00167 struct nl_cache *nl_cache_alloc(void)
{
      struct nl_cache *cache;

      cache = calloc(1, sizeof(*cache));
      if (!cache) {
            nl_errno(ENOMEM);
            return NULL;
      }

      nl_init_list_head(&cache->c_items);

      return cache;
}

/**
 * Allocate an empty cache based on cache operations
 * @arg ops       cache operations to base the cache on
 * @return A newly allocated and initialized cache.
 */
00187 struct nl_cache *nl_cache_alloc_from_ops(struct nl_cache_ops *ops)
{
      struct nl_cache *new;

      new = nl_cache_alloc();
      if (!new)
            return NULL;

      new->c_ops = ops;

      return new;
}

/**
 * Allocate an empty cache based on type name
 * @arg kind            Name of cache type
 * @return A newly allocated and initialized cache.
 */
00205 struct nl_cache *nl_cache_alloc_name(const char *kind)
{
      struct nl_cache_ops *ops;

      ops = nl_cache_mngt_lookup(kind);
      if (!ops) {
            nl_error(ENOENT, "Unable to lookup cache \"%s\"", kind);
            return NULL;
      }

      return nl_cache_alloc_from_ops(ops);
}

/**
 * Destroy a cache.
 * @arg cache           cache to destroy
 *
 * Removes all elements of a cache and destroys the cache by freeing all
 * internal memory allocations.
 */
00225 void nl_cache_destroy(struct nl_cache *cache)
{
      struct nl_object *obj, *tmp;

      NL_DBG(1, "Destroying cache %p...\n", cache);

      nl_list_for_each_entry_safe(obj, tmp, &cache->c_items, ce_list)
            nl_cache_delete(cache, obj);
}

/**
 * Destroy and free a cache.
 * @arg cache           cache to destroy
 *
 * Removes all elements of a cache and destroys the cache by freeing all
 * internal memory allocations. Additionally the cache itself gets
 * freed.
 *
 * @note Use this function if you are working with allocated caches.
 */
00245 void nl_cache_destroy_and_free(struct nl_cache *cache)
{
      NL_DBG(1, "Destroying and freeing cache %p...\n", cache);
      nl_cache_destroy(cache);
      free(cache);
}

/** @} */

/**
 * @name Cache Modifications
 * @{
 */

/**
 * Add an element to the cache.
 * @arg cache           cache to add a element to
 * @arg obj       Common obj to be added to the cache
 *
 * Adds the object \c obj to the tail of the cache \c cache and. The
 * cache is enlarged as needed.
 *
 * @return 0 or a negative error code.
 */
00269 int nl_cache_add(struct nl_cache *cache, struct nl_object *obj)
{
      struct nl_object *new;

      if (nl_object_shared(obj)) {
            new = nl_object_clone(obj);
            if (!new)
                  return nl_errno(ENOMEM);

            nl_object_put(obj);
      } else
            new = obj;

      new->ce_cache = cache;

      nl_list_add_tail(&new->ce_list, &cache->c_items);
      cache->c_nitems++;

      NL_DBG(1, "Added %p to cache %p.\n", new, cache);

      return 0;
}

static int subsys_parse_cb(struct nl_object *c, struct nl_parser_param *p)
{
      return nl_cache_add((struct nl_cache *) p->pp_arg, c);
}

/** @cond SKIP */
int nl_cache_parse(struct nl_cache_ops *ops, struct sockaddr_nl *who,
               struct nlmsghdr *nlh, struct nl_parser_param *params)
{
      int i, len, err, hdrsize;

      hdrsize = ops->co_hdrsize;
      len = nlh->nlmsg_len - nlmsg_msg_size(hdrsize);
      if (len < 0) {
            err = nl_error(EINVAL, "netlink message too short to "
                               "of kind %s", ops->co_name);
            goto errout;
      }

      for (i = 0; ops->co_msgtypes[i].mt_id >= 0; i++)
            if (ops->co_msgtypes[i].mt_id == nlh->nlmsg_type)
                  return ops->co_msg_parser(who, nlh, params);

      err = nl_error(EINVAL, "Unsupported netlink message type %d",
                   nlh->nlmsg_type);
errout:
      return err;
}
/** @endcond */

/**
 * Parse a netlink message and add it to the cache.
 * @arg cache           cache to add element to
 * @arg msg       netlink message
 *
 * Parses a netlink message by calling the cache specific message parser
 * and adds the new element to the cache.
 *
 * @return 0 or a negative error code.
 */
00332 int nl_cache_parse_and_add(struct nl_cache *cache, struct nl_msg *msg)
{
      struct nl_parser_param p = {
            .pp_cb = subsys_parse_cb,
            .pp_arg = cache,
      };

      return nl_cache_parse(cache->c_ops, NULL, nlmsg_hdr(msg), &p);
}

/**
 * Delete an element from a cache.
 * @arg cache           cache to delete the element from
 * @arg obj       Object to delete
 *
 * Deletes the object \c obj from the cache \c cache.
 */
00349 void nl_cache_delete(struct nl_cache *cache, struct nl_object *obj)
{
      if (obj->ce_cache != cache)
            BUG();

      nl_list_del(&obj->ce_list);
      nl_object_put(obj);
      cache->c_nitems--;
      obj->ce_cache = NULL;

      NL_DBG(1, "Deleted %p from cache %p.\n", obj, cache);
}

/** @cond SKIP */
struct update_xdata {
      struct nl_cache_ops *ops;
      struct nl_parser_param *params;
};
/** @endcond */

00369 static int update_msg_parser(struct nl_msg *msg, void *arg)
{
      struct update_xdata *x = arg;
      
      return nl_cache_parse(x->ops, &msg->nm_src, msg->nm_nlh, x->params);
}

/**
 * Pickup a netlink dump response and put it into a cache.
 * @arg handle          Netlink handle.
 * @arg cache           Cache to put items into.
 *
 * Waits for netlink messages to arrive, parses them and puts them into
 * the specified cache.
 *
 * @return 0 or a negative error code.
 */
00386 int nl_cache_pickup(struct nl_handle *handle, struct nl_cache *cache)
{
      int err;
      struct nl_cache_ops *ops = cache->c_ops;
      struct nl_cb *cb;
      struct nl_parser_param p = {
            .pp_cb = subsys_parse_cb,
            .pp_arg = cache,
      };
      struct update_xdata x = {
            .ops = ops,
            .params = &p,
      };

      NL_DBG(1, "Filling cache %p...\n", cache);

      cb = nl_cb_clone(nl_handle_get_cb(handle));
      nl_cb_set(cb, NL_CB_VALID, NL_CB_CUSTOM, update_msg_parser, &x);

      err = nl_recvmsgs(handle, cb);
      nl_cb_destroy(cb);

      return err;
}

/**
 * Update (synchronize) a local cache with the kernel.
 * @arg handle          netlink handle
 * @arg cache           cache to update
 *
 * Updates the local cache \c cache with the state in the kernel. During
 * this process the cache gets emptied and refilled with the new content
 * received from the kernel.
 *
 * @return 0 or a negative error code.
 */
00422 int nl_cache_update(struct nl_handle *handle, struct nl_cache *cache)
{
      int err;
      struct nl_cache_ops *ops = cache->c_ops;

      err = ops->co_request_update(cache, handle);
      if (err < 0)
            return err;

      NL_DBG(2, "Upading cache %p, request sent, waiting for dump...\n",
             cache);

      nl_cache_destroy(cache);

      return nl_cache_pickup(handle, cache);
}

/** @} */

/**
 * @name Dumping
 * @{
 */

/**
 * Dump all elements of a cache.
 * @arg cache           cache to dump
 * @arg params          dumping parameters
 *
 * Dumps all elements of the \a cache to the file descriptor \a fd.
 */
00453 void nl_cache_dump(struct nl_cache *cache, struct nl_dump_params *params)
{
      NL_DBG(1, "Dumping cache %p\n", cache);
      nl_cache_dump_filter(cache, params, NULL);
}

/**
 * Dump all elements of a cache (filtered).
 * @arg cache           cache to dump
 * @arg params          dumping parameters (optional)
 * @arg filter          filter object
 *
 * Dumps all elements of the \a cache to the file descriptor \a fd
 * given they match the given filter \a filter.
 */
00468 void nl_cache_dump_filter(struct nl_cache *cache,
                    struct nl_dump_params *params,
                    struct nl_object *filter)
{
      int type = params ? params->dp_type : NL_DUMP_FULL;
      struct nl_cache_ops *ops = cache->c_ops;
      struct nl_object *obj;

      if (type > NL_DUMP_MAX || type < 0)
            BUG();

      if (!ops->co_dump[type])
            return;

      nl_list_for_each_entry(obj, &cache->c_items, ce_list) {
            if (filter && obj->ce_ops != filter->ce_ops)
                  continue;
            
            if (filter && ops->co_filter && !ops->co_filter(obj, filter))
                  continue;

            dump_from_ops(obj, params);
      }
}

/** @} */

/**
 * @name Iterators
 * @{
 */

/**
 * Call a callback on each element of the cache.
 * @arg cache           cache to iterate on
 * @arg cb        callback function
 * @arg arg       argument passed to callback function
 *
 * Calls a callback function \a cb on each element of the \a cache.
 * The argument \a arg is passed on the callback function.
 */
00509 void nl_cache_foreach(struct nl_cache *cache,
                  void (*cb)(struct nl_object *, void *), void *arg)
{
      nl_cache_foreach_filter(cache, NULL, cb, arg);
}

/**
 * Call a callback on each element of the cache (filtered).
 * @arg cache           cache to iterate on
 * @arg filter          filter object
 * @arg cb        callback function
 * @arg arg       argument passed to callback function
 *
 * Calls a callback function \a cb on each element of the \a cache
 * that matches the \a filter. The argument \a arg is passed on
 * to the callback function.
 */
00526 void nl_cache_foreach_filter(struct nl_cache *cache, struct nl_object *filter,
                       void (*cb)(struct nl_object *, void *), void *arg)
{
      struct nl_object *obj, *tmp;
      struct nl_cache_ops *ops = cache->c_ops;

      nl_list_for_each_entry_safe(obj, tmp, &cache->c_items, ce_list) {
            if (filter && ops->co_filter && !ops->co_filter(obj, filter))
                  continue;

            cb(obj, arg);
      }
}

/** @} */

/** @} */

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