Root/package/libnl-tiny/src/cache.c

1/*
2 * lib/cache.c Caching Module
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 cache_mngt
14 * @defgroup cache Cache
15 *
16 * @code
17 * Cache Management | | Type Specific Cache Operations
18 *
19 * | | +----------------+ +------------+
20 * | request update | | msg_parser |
21 * | | +----------------+ +------------+
22 * +- - - - -^- - - - - - - -^- -|- - - -
23 * nl_cache_update: | | | |
24 * 1) --------- co_request_update ------+ | |
25 * | | |
26 * 2) destroy old cache +----------- pp_cb ---------|---+
27 * | | |
28 * 3) ---------- nl_recvmsgs ----------+ +- cb_valid -+
29 * +--------------+ | | | |
30 * | nl_cache_add |<-----+ + - - -v- -|- - - - - - - - - - -
31 * +--------------+ | | +-------------+
32 * | nl_recvmsgs |
33 * | | +-----|-^-----+
34 * +---v-|---+
35 * | | | nl_recv |
36 * +---------+
37 * | | Core Netlink
38 * @endcode
39 *
40 * @{
41 */
42
43#include <netlink-local.h>
44#include <netlink/netlink.h>
45#include <netlink/cache.h>
46#include <netlink/object.h>
47#include <netlink/utils.h>
48
49/**
50 * @name Access Functions
51 * @{
52 */
53
54#ifdef disabled
55/**
56 * Return the number of items in the cache
57 * @arg cache cache handle
58 */
59int nl_cache_nitems(struct nl_cache *cache)
60{
61    return cache->c_nitems;
62}
63
64/**
65 * Return the number of items matching a filter in the cache
66 * @arg cache Cache object.
67 * @arg filter Filter object.
68 */
69int nl_cache_nitems_filter(struct nl_cache *cache, struct nl_object *filter)
70{
71    struct nl_object_ops *ops;
72    struct nl_object *obj;
73    int nitems = 0;
74
75    if (cache->c_ops == NULL)
76        BUG();
77
78    ops = cache->c_ops->co_obj_ops;
79    
80    nl_list_for_each_entry(obj, &cache->c_items, ce_list) {
81        if (filter && !nl_object_match_filter(obj, filter))
82            continue;
83
84        nitems++;
85    }
86
87    return nitems;
88}
89
90/**
91 * Returns \b true if the cache is empty.
92 * @arg cache Cache to check
93 * @return \a true if the cache is empty, otherwise \b false is returned.
94 */
95int nl_cache_is_empty(struct nl_cache *cache)
96{
97    return nl_list_empty(&cache->c_items);
98}
99
100/**
101 * Return the operations set of the cache
102 * @arg cache cache handle
103 */
104struct nl_cache_ops *nl_cache_get_ops(struct nl_cache *cache)
105{
106    return cache->c_ops;
107}
108
109/**
110 * Return the first element in the cache
111 * @arg cache cache handle
112 */
113struct nl_object *nl_cache_get_first(struct nl_cache *cache)
114{
115    if (nl_list_empty(&cache->c_items))
116        return NULL;
117
118    return nl_list_entry(cache->c_items.next,
119                 struct nl_object, ce_list);
120}
121
122/**
123 * Return the last element in the cache
124 * @arg cache cache handle
125 */
126struct nl_object *nl_cache_get_last(struct nl_cache *cache)
127{
128    if (nl_list_empty(&cache->c_items))
129        return NULL;
130
131    return nl_list_entry(cache->c_items.prev,
132                 struct nl_object, ce_list);
133}
134
135/**
136 * Return the next element in the cache
137 * @arg obj current object
138 */
139struct nl_object *nl_cache_get_next(struct nl_object *obj)
140{
141    if (nl_list_at_tail(obj, &obj->ce_cache->c_items, ce_list))
142        return NULL;
143    else
144        return nl_list_entry(obj->ce_list.next,
145                     struct nl_object, ce_list);
146}
147
148/**
149 * Return the previous element in the cache
150 * @arg obj current object
151 */
152struct nl_object *nl_cache_get_prev(struct nl_object *obj)
153{
154    if (nl_list_at_head(obj, &obj->ce_cache->c_items, ce_list))
155        return NULL;
156    else
157        return nl_list_entry(obj->ce_list.prev,
158                     struct nl_object, ce_list);
159}
160#endif
161
162/** @} */
163
164/**
165 * @name Cache Creation/Deletion
166 * @{
167 */
168
169/**
170 * Allocate an empty cache
171 * @arg ops cache operations to base the cache on
172 *
173 * @return A newly allocated and initialized cache.
174 */
175struct nl_cache *nl_cache_alloc(struct nl_cache_ops *ops)
176{
177    struct nl_cache *cache;
178
179    cache = calloc(1, sizeof(*cache));
180    if (!cache)
181        return NULL;
182
183    nl_init_list_head(&cache->c_items);
184    cache->c_ops = ops;
185
186    NL_DBG(2, "Allocated cache %p <%s>.\n", cache, nl_cache_name(cache));
187
188    return cache;
189}
190
191int nl_cache_alloc_and_fill(struct nl_cache_ops *ops, struct nl_sock *sock,
192                struct nl_cache **result)
193{
194    struct nl_cache *cache;
195    int err;
196    
197    if (!(cache = nl_cache_alloc(ops)))
198        return -NLE_NOMEM;
199
200    if (sock && (err = nl_cache_refill(sock, cache)) < 0) {
201        nl_cache_free(cache);
202        return err;
203    }
204
205    *result = cache;
206    return 0;
207}
208
209#ifdef disabled
210/**
211 * Allocate an empty cache based on type name
212 * @arg kind Name of cache type
213 * @return A newly allocated and initialized cache.
214 */
215int nl_cache_alloc_name(const char *kind, struct nl_cache **result)
216{
217    struct nl_cache_ops *ops;
218    struct nl_cache *cache;
219
220    ops = nl_cache_ops_lookup(kind);
221    if (!ops)
222        return -NLE_NOCACHE;
223
224    if (!(cache = nl_cache_alloc(ops)))
225        return -NLE_NOMEM;
226
227    *result = cache;
228    return 0;
229}
230
231/**
232 * Allocate a new cache containing a subset of a cache
233 * @arg orig Original cache to be based on
234 * @arg filter Filter defining the subset to be filled into new cache
235 * @return A newly allocated cache or NULL.
236 */
237struct nl_cache *nl_cache_subset(struct nl_cache *orig,
238                 struct nl_object *filter)
239{
240    struct nl_cache *cache;
241    struct nl_object_ops *ops;
242    struct nl_object *obj;
243
244    if (!filter)
245        BUG();
246
247    cache = nl_cache_alloc(orig->c_ops);
248    if (!cache)
249        return NULL;
250
251    ops = orig->c_ops->co_obj_ops;
252
253    nl_list_for_each_entry(obj, &orig->c_items, ce_list) {
254        if (!nl_object_match_filter(obj, filter))
255            continue;
256
257        nl_cache_add(cache, obj);
258    }
259
260    return cache;
261}
262#endif
263
264/**
265 * Clear a cache.
266 * @arg cache cache to clear
267 *
268 * Removes all elements of a cache.
269 */
270void nl_cache_clear(struct nl_cache *cache)
271{
272    struct nl_object *obj, *tmp;
273
274    NL_DBG(1, "Clearing cache %p <%s>...\n", cache, nl_cache_name(cache));
275
276    nl_list_for_each_entry_safe(obj, tmp, &cache->c_items, ce_list)
277        nl_cache_remove(obj);
278}
279
280/**
281 * Free a cache.
282 * @arg cache Cache to free.
283 *
284 * Removes all elements of a cache and frees all memory.
285 *
286 * @note Use this function if you are working with allocated caches.
287 */
288void nl_cache_free(struct nl_cache *cache)
289{
290    if (!cache)
291        return;
292
293    nl_cache_clear(cache);
294    NL_DBG(1, "Freeing cache %p <%s>...\n", cache, nl_cache_name(cache));
295    free(cache);
296}
297
298/** @} */
299
300/**
301 * @name Cache Modifications
302 * @{
303 */
304
305static int __cache_add(struct nl_cache *cache, struct nl_object *obj)
306{
307    obj->ce_cache = cache;
308
309    nl_list_add_tail(&obj->ce_list, &cache->c_items);
310    cache->c_nitems++;
311
312    NL_DBG(1, "Added %p to cache %p <%s>.\n",
313           obj, cache, nl_cache_name(cache));
314
315    return 0;
316}
317
318/**
319 * Add object to a cache.
320 * @arg cache Cache to add object to
321 * @arg obj Object to be added to the cache
322 *
323 * Adds the given object to the specified cache. The object is cloned
324 * if it has been added to another cache already.
325 *
326 * @return 0 or a negative error code.
327 */
328int nl_cache_add(struct nl_cache *cache, struct nl_object *obj)
329{
330    struct nl_object *new;
331
332    if (cache->c_ops->co_obj_ops != obj->ce_ops)
333        return -NLE_OBJ_MISMATCH;
334
335    if (!nl_list_empty(&obj->ce_list)) {
336        new = nl_object_clone(obj);
337        if (!new)
338            return -NLE_NOMEM;
339    } else {
340        nl_object_get(obj);
341        new = obj;
342    }
343
344    return __cache_add(cache, new);
345}
346
347#ifdef disabled
348/**
349 * Move object from one cache to another
350 * @arg cache Cache to move object to.
351 * @arg obj Object subject to be moved
352 *
353 * Removes the given object from its associated cache if needed
354 * and adds it to the new cache.
355 *
356 * @return 0 on success or a negative error code.
357 */
358int nl_cache_move(struct nl_cache *cache, struct nl_object *obj)
359{
360    if (cache->c_ops->co_obj_ops != obj->ce_ops)
361        return -NLE_OBJ_MISMATCH;
362
363    NL_DBG(3, "Moving object %p to cache %p\n", obj, cache);
364    
365    /* Acquire reference, if already in a cache this will be
366     * reverted during removal */
367    nl_object_get(obj);
368
369    if (!nl_list_empty(&obj->ce_list))
370        nl_cache_remove(obj);
371
372    return __cache_add(cache, obj);
373}
374#endif
375
376/**
377 * Removes an object from a cache.
378 * @arg obj Object to remove from its cache
379 *
380 * Removes the object \c obj from the cache it is assigned to, since
381 * an object can only be assigned to one cache at a time, the cache
382 * must ne be passed along with it.
383 */
384void nl_cache_remove(struct nl_object *obj)
385{
386    struct nl_cache *cache = obj->ce_cache;
387
388    if (cache == NULL)
389        return;
390
391    nl_list_del(&obj->ce_list);
392    obj->ce_cache = NULL;
393    nl_object_put(obj);
394    cache->c_nitems--;
395
396    NL_DBG(1, "Deleted %p from cache %p <%s>.\n",
397           obj, cache, nl_cache_name(cache));
398}
399
400#ifdef disabled
401/**
402 * Search for an object in a cache
403 * @arg cache Cache to search in.
404 * @arg needle Object to look for.
405 *
406 * Iterates over the cache and looks for an object with identical
407 * identifiers as the needle.
408 *
409 * @return Reference to object or NULL if not found.
410 * @note The returned object must be returned via nl_object_put().
411 */
412struct nl_object *nl_cache_search(struct nl_cache *cache,
413                  struct nl_object *needle)
414{
415    struct nl_object *obj;
416
417    nl_list_for_each_entry(obj, &cache->c_items, ce_list) {
418        if (nl_object_identical(obj, needle)) {
419            nl_object_get(obj);
420            return obj;
421        }
422    }
423
424    return NULL;
425}
426#endif
427
428/** @} */
429
430/**
431 * @name Synchronization
432 * @{
433 */
434
435/**
436 * Request a full dump from the kernel to fill a cache
437 * @arg sk Netlink socket.
438 * @arg cache Cache subjected to be filled.
439 *
440 * Send a dumping request to the kernel causing it to dump all objects
441 * related to the specified cache to the netlink socket.
442 *
443 * Use nl_cache_pickup() to read the objects from the socket and fill them
444 * into a cache.
445 */
446int nl_cache_request_full_dump(struct nl_sock *sk, struct nl_cache *cache)
447{
448    NL_DBG(2, "Requesting dump from kernel for cache %p <%s>...\n",
449              cache, nl_cache_name(cache));
450
451    if (cache->c_ops->co_request_update == NULL)
452        return -NLE_OPNOTSUPP;
453
454    return cache->c_ops->co_request_update(cache, sk);
455}
456
457/** @cond SKIP */
458struct update_xdata {
459    struct nl_cache_ops *ops;
460    struct nl_parser_param *params;
461};
462
463static int update_msg_parser(struct nl_msg *msg, void *arg)
464{
465    struct update_xdata *x = arg;
466    
467    return nl_cache_parse(x->ops, &msg->nm_src, msg->nm_nlh, x->params);
468}
469/** @endcond */
470
471int __cache_pickup(struct nl_sock *sk, struct nl_cache *cache,
472           struct nl_parser_param *param)
473{
474    int err;
475    struct nl_cb *cb;
476    struct update_xdata x = {
477        .ops = cache->c_ops,
478        .params = param,
479    };
480
481    NL_DBG(1, "Picking up answer for cache %p <%s>...\n",
482          cache, nl_cache_name(cache));
483
484    cb = nl_cb_clone(sk->s_cb);
485    if (cb == NULL)
486        return -NLE_NOMEM;
487
488    nl_cb_set(cb, NL_CB_VALID, NL_CB_CUSTOM, update_msg_parser, &x);
489
490    err = nl_recvmsgs(sk, cb);
491    if (err < 0)
492        NL_DBG(2, "While picking up for %p <%s>, recvmsgs() returned " \
493               "%d: %s", cache, nl_cache_name(cache),
494               err, nl_geterror(err));
495
496    nl_cb_put(cb);
497
498    return err;
499}
500
501static int pickup_cb(struct nl_object *c, struct nl_parser_param *p)
502{
503    return nl_cache_add((struct nl_cache *) p->pp_arg, c);
504}
505
506/**
507 * Pickup a netlink dump response and put it into a cache.
508 * @arg sk Netlink socket.
509 * @arg cache Cache to put items into.
510 *
511 * Waits for netlink messages to arrive, parses them and puts them into
512 * the specified cache.
513 *
514 * @return 0 on success or a negative error code.
515 */
516int nl_cache_pickup(struct nl_sock *sk, struct nl_cache *cache)
517{
518    struct nl_parser_param p = {
519        .pp_cb = pickup_cb,
520        .pp_arg = cache,
521    };
522
523    return __cache_pickup(sk, cache, &p);
524}
525
526#ifdef disabled
527static int cache_include(struct nl_cache *cache, struct nl_object *obj,
528             struct nl_msgtype *type, change_func_t cb)
529{
530    struct nl_object *old;
531
532    switch (type->mt_act) {
533    case NL_ACT_NEW:
534    case NL_ACT_DEL:
535        old = nl_cache_search(cache, obj);
536        if (old) {
537            nl_cache_remove(old);
538            if (type->mt_act == NL_ACT_DEL) {
539                if (cb)
540                    cb(cache, old, NL_ACT_DEL);
541                nl_object_put(old);
542            }
543        }
544
545        if (type->mt_act == NL_ACT_NEW) {
546            nl_cache_move(cache, obj);
547            if (old == NULL && cb)
548                cb(cache, obj, NL_ACT_NEW);
549            else if (old) {
550                if (nl_object_diff(old, obj) && cb)
551                    cb(cache, obj, NL_ACT_CHANGE);
552
553                nl_object_put(old);
554            }
555        }
556        break;
557    default:
558        NL_DBG(2, "Unknown action associated to object %p\n", obj);
559        return 0;
560    }
561
562    return 0;
563}
564
565int nl_cache_include(struct nl_cache *cache, struct nl_object *obj,
566             change_func_t change_cb)
567{
568    struct nl_cache_ops *ops = cache->c_ops;
569    int i;
570
571    if (ops->co_obj_ops != obj->ce_ops)
572        return -NLE_OBJ_MISMATCH;
573
574    for (i = 0; ops->co_msgtypes[i].mt_id >= 0; i++)
575        if (ops->co_msgtypes[i].mt_id == obj->ce_msgtype)
576            return cache_include(cache, obj, &ops->co_msgtypes[i],
577                         change_cb);
578
579    return -NLE_MSGTYPE_NOSUPPORT;
580}
581
582static int resync_cb(struct nl_object *c, struct nl_parser_param *p)
583{
584    struct nl_cache_assoc *ca = p->pp_arg;
585
586    return nl_cache_include(ca->ca_cache, c, ca->ca_change);
587}
588
589int nl_cache_resync(struct nl_sock *sk, struct nl_cache *cache,
590            change_func_t change_cb)
591{
592    struct nl_object *obj, *next;
593    struct nl_cache_assoc ca = {
594        .ca_cache = cache,
595        .ca_change = change_cb,
596    };
597    struct nl_parser_param p = {
598        .pp_cb = resync_cb,
599        .pp_arg = &ca,
600    };
601    int err;
602
603    NL_DBG(1, "Resyncing cache %p <%s>...\n", cache, nl_cache_name(cache));
604
605    /* Mark all objects so we can see if some of them are obsolete */
606    nl_cache_mark_all(cache);
607
608    err = nl_cache_request_full_dump(sk, cache);
609    if (err < 0)
610        goto errout;
611
612    err = __cache_pickup(sk, cache, &p);
613    if (err < 0)
614        goto errout;
615
616    nl_list_for_each_entry_safe(obj, next, &cache->c_items, ce_list)
617        if (nl_object_is_marked(obj))
618            nl_cache_remove(obj);
619
620    NL_DBG(1, "Finished resyncing %p <%s>\n", cache, nl_cache_name(cache));
621
622    err = 0;
623errout:
624    return err;
625}
626#endif
627
628/** @} */
629
630/**
631 * @name Parsing
632 * @{
633 */
634
635/** @cond SKIP */
636int nl_cache_parse(struct nl_cache_ops *ops, struct sockaddr_nl *who,
637           struct nlmsghdr *nlh, struct nl_parser_param *params)
638{
639    int i, err;
640
641    if (!nlmsg_valid_hdr(nlh, ops->co_hdrsize))
642        return -NLE_MSG_TOOSHORT;
643
644    for (i = 0; ops->co_msgtypes[i].mt_id >= 0; i++) {
645        if (ops->co_msgtypes[i].mt_id == nlh->nlmsg_type) {
646            err = ops->co_msg_parser(ops, who, nlh, params);
647            if (err != -NLE_OPNOTSUPP)
648                goto errout;
649        }
650    }
651
652
653    err = -NLE_MSGTYPE_NOSUPPORT;
654errout:
655    return err;
656}
657/** @endcond */
658
659/**
660 * Parse a netlink message and add it to the cache.
661 * @arg cache cache to add element to
662 * @arg msg netlink message
663 *
664 * Parses a netlink message by calling the cache specific message parser
665 * and adds the new element to the cache.
666 *
667 * @return 0 or a negative error code.
668 */
669int nl_cache_parse_and_add(struct nl_cache *cache, struct nl_msg *msg)
670{
671    struct nl_parser_param p = {
672        .pp_cb = pickup_cb,
673        .pp_arg = cache,
674    };
675
676    return nl_cache_parse(cache->c_ops, NULL, nlmsg_hdr(msg), &p);
677}
678
679/**
680 * (Re)fill a cache with the contents in the kernel.
681 * @arg sk Netlink socket.
682 * @arg cache cache to update
683 *
684 * Clears the specified cache and fills it with the current state in
685 * the kernel.
686 *
687 * @return 0 or a negative error code.
688 */
689int nl_cache_refill(struct nl_sock *sk, struct nl_cache *cache)
690{
691    int err;
692
693    err = nl_cache_request_full_dump(sk, cache);
694    if (err < 0)
695        return err;
696
697    NL_DBG(2, "Upading cache %p <%s>, request sent, waiting for dump...\n",
698           cache, nl_cache_name(cache));
699    nl_cache_clear(cache);
700
701    return nl_cache_pickup(sk, cache);
702}
703
704/** @} */
705#ifdef disabled
706
707/**
708 * @name Utillities
709 * @{
710 */
711
712/**
713 * Mark all objects in a cache
714 * @arg cache Cache to mark all objects in
715 */
716void nl_cache_mark_all(struct nl_cache *cache)
717{
718    struct nl_object *obj;
719
720    NL_DBG(2, "Marking all objects in cache %p <%s>...\n",
721              cache, nl_cache_name(cache));
722
723    nl_list_for_each_entry(obj, &cache->c_items, ce_list)
724        nl_object_mark(obj);
725}
726
727/** @} */
728
729/**
730 * @name Dumping
731 * @{
732 */
733/**
734 * Dump all elements of a cache.
735 * @arg cache cache to dump
736 * @arg params dumping parameters
737 *
738 * Dumps all elements of the \a cache to the file descriptor \a fd.
739 */
740void nl_cache_dump(struct nl_cache *cache, struct nl_dump_params *params)
741{
742    nl_cache_dump_filter(cache, params, NULL);
743}
744
745/**
746 * Dump all elements of a cache (filtered).
747 * @arg cache cache to dump
748 * @arg params dumping parameters (optional)
749 * @arg filter filter object
750 *
751 * Dumps all elements of the \a cache to the file descriptor \a fd
752 * given they match the given filter \a filter.
753 */
754void nl_cache_dump_filter(struct nl_cache *cache,
755              struct nl_dump_params *params,
756              struct nl_object *filter)
757{
758    int type = params ? params->dp_type : NL_DUMP_DETAILS;
759    struct nl_object_ops *ops;
760    struct nl_object *obj;
761
762    NL_DBG(2, "Dumping cache %p <%s> filter %p\n",
763           cache, nl_cache_name(cache), filter);
764
765    if (type > NL_DUMP_MAX || type < 0)
766        BUG();
767
768    if (cache->c_ops == NULL)
769        BUG();
770
771    ops = cache->c_ops->co_obj_ops;
772    if (!ops->oo_dump[type])
773        return;
774
775    nl_list_for_each_entry(obj, &cache->c_items, ce_list) {
776        if (filter && !nl_object_match_filter(obj, filter))
777            continue;
778
779        NL_DBG(4, "Dumping object %p...\n", obj);
780        dump_from_ops(obj, params);
781    }
782}
783
784/** @} */
785
786/**
787 * @name Iterators
788 * @{
789 */
790
791/**
792 * Call a callback on each element of the cache.
793 * @arg cache cache to iterate on
794 * @arg cb callback function
795 * @arg arg argument passed to callback function
796 *
797 * Calls a callback function \a cb on each element of the \a cache.
798 * The argument \a arg is passed on the callback function.
799 */
800void nl_cache_foreach(struct nl_cache *cache,
801              void (*cb)(struct nl_object *, void *), void *arg)
802{
803    nl_cache_foreach_filter(cache, NULL, cb, arg);
804}
805
806/**
807 * Call a callback on each element of the cache (filtered).
808 * @arg cache cache to iterate on
809 * @arg filter filter object
810 * @arg cb callback function
811 * @arg arg argument passed to callback function
812 *
813 * Calls a callback function \a cb on each element of the \a cache
814 * that matches the \a filter. The argument \a arg is passed on
815 * to the callback function.
816 */
817void nl_cache_foreach_filter(struct nl_cache *cache, struct nl_object *filter,
818                 void (*cb)(struct nl_object *, void *), void *arg)
819{
820    struct nl_object *obj, *tmp;
821    struct nl_object_ops *ops;
822
823    if (cache->c_ops == NULL)
824        BUG();
825
826    ops = cache->c_ops->co_obj_ops;
827
828    nl_list_for_each_entry_safe(obj, tmp, &cache->c_items, ce_list) {
829        if (filter && !nl_object_match_filter(obj, filter))
830            continue;
831
832        cb(obj, arg);
833    }
834}
835
836/** @} */
837#endif
838
839/** @} */
840

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