source: trunk/server/source3/lib/gencache.c@ 966

Last change on this file since 966 was 745, checked in by Silvan Scherrer, 13 years ago

Samba Server: updated trunk to 3.6.0
File size: 18.8 KB
Line 
1/*
2 Unix SMB/CIFS implementation.
3
4 Generic, persistent and shared between processes cache mechanism for use
5 by various parts of the Samba code
6
7 Copyright (C) Rafal Szczesniak 2002
8 Copyright (C) Volker Lendecke 2009
9
10 This program is free software; you can redistribute it and/or modify
11 it under the terms of the GNU General Public License as published by
12 the Free Software Foundation; either version 3 of the License, or
13 (at your option) any later version.
14
15 This program is distributed in the hope that it will be useful,
16 but WITHOUT ANY WARRANTY; without even the implied warranty of
17 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
18 GNU General Public License for more details.
19
20 You should have received a copy of the GNU General Public License
21 along with this program. If not, see <http://www.gnu.org/licenses/>.
22*/
23
24#include "includes.h"
25#include "system/filesys.h"
26#include "system/glob.h"
27#include "util_tdb.h"
28
29#undef DBGC_CLASS
30#define DBGC_CLASS DBGC_TDB
31
32#define TIMEOUT_LEN 12
33#define CACHE_DATA_FMT "%12u/"
34#define READ_CACHE_DATA_FMT_TEMPLATE "%%12u/%%%us"
35#define BLOB_TYPE "DATA_BLOB"
36#define BLOB_TYPE_LEN 9
37
38static struct tdb_context *cache;
39static struct tdb_context *cache_notrans;
40
41/**
42 * @file gencache.c
43 * @brief Generic, persistent and shared between processes cache mechanism
44 * for use by various parts of the Samba code
45 *
46 **/
47
48
49/**
50 * Cache initialisation function. Opens cache tdb file or creates
51 * it if does not exist.
52 *
53 * @return true on successful initialisation of the cache or
54 * false on failure
55 **/
56
57static bool gencache_init(void)
58{
59 char* cache_fname = NULL;
60 int open_flags = O_RDWR|O_CREAT;
61 bool first_try = true;
62
63 /* skip file open if it's already opened */
64 if (cache) return True;
65
66 cache_fname = lock_path("gencache.tdb");
67
68 DEBUG(5, ("Opening cache file at %s\n", cache_fname));
69
70again:
71 cache = tdb_open_log(cache_fname, 0, TDB_DEFAULT|TDB_INCOMPATIBLE_HASH, open_flags, 0644);
72 if (cache) {
73 int ret;
74 ret = tdb_check(cache, NULL, NULL);
75 if (ret != 0) {
76 tdb_close(cache);
77 cache = NULL;
78 if (!first_try) {
79 DEBUG(0, ("gencache_init: tdb_check(%s) failed\n",
80 cache_fname));
81 return false;
82 }
83 first_try = false;
84 DEBUG(0, ("gencache_init: tdb_check(%s) failed - retry after CLEAR_IF_FIRST\n",
85 cache_fname));
86 cache = tdb_open_log(cache_fname, 0, TDB_CLEAR_IF_FIRST|TDB_INCOMPATIBLE_HASH, open_flags, 0644);
87 if (cache) {
88 tdb_close(cache);
89 cache = NULL;
90 goto again;
91 }
92 }
93 }
94
95 if (!cache && (errno == EACCES)) {
96 open_flags = O_RDONLY;
97 cache = tdb_open_log(cache_fname, 0, TDB_DEFAULT|TDB_INCOMPATIBLE_HASH, open_flags,
98 0644);
99 if (cache) {
100 DEBUG(5, ("gencache_init: Opening cache file %s read-only.\n", cache_fname));
101 }
102 }
103
104 if (!cache) {
105 DEBUG(5, ("Attempt to open gencache.tdb has failed.\n"));
106 return False;
107 }
108
109 cache_fname = lock_path("gencache_notrans.tdb");
110
111 DEBUG(5, ("Opening cache file at %s\n", cache_fname));
112
113 cache_notrans = tdb_open_log(cache_fname, 0, TDB_CLEAR_IF_FIRST|TDB_INCOMPATIBLE_HASH,
114 open_flags, 0644);
115 if (cache_notrans == NULL) {
116 DEBUG(5, ("Opening %s failed: %s\n", cache_fname,
117 strerror(errno)));
118 tdb_close(cache);
119 cache = NULL;
120 return false;
121 }
122
123 return True;
124}
125
126static TDB_DATA last_stabilize_key(void)
127{
128 TDB_DATA result;
129 result.dptr = (uint8_t *)"@LAST_STABILIZED";
130 result.dsize = 17;
131 return result;
132}
133
134/**
135 * Set an entry in the cache file. If there's no such
136 * one, then add it.
137 *
138 * @param keystr string that represents a key of this entry
139 * @param blob DATA_BLOB value being cached
140 * @param timeout time when the value is expired
141 *
142 * @retval true when entry is successfuly stored
143 * @retval false on failure
144 **/
145
146bool gencache_set_data_blob(const char *keystr, const DATA_BLOB *blob,
147 time_t timeout)
148{
149 int ret;
150 TDB_DATA databuf;
151 char* val;
152 time_t last_stabilize;
153 static int writecount;
154
155 if (tdb_data_cmp(string_term_tdb_data(keystr),
156 last_stabilize_key()) == 0) {
157 DEBUG(10, ("Can't store %s as a key\n", keystr));
158 return false;
159 }
160
161 if ((keystr == NULL) || (blob == NULL)) {
162 return false;
163 }
164
165 if (!gencache_init()) return False;
166
167 val = talloc_asprintf(talloc_tos(), CACHE_DATA_FMT, (int)timeout);
168 if (val == NULL) {
169 return False;
170 }
171 val = talloc_realloc(NULL, val, char, talloc_array_length(val)-1);
172 if (val == NULL) {
173 return false;
174 }
175 val = (char *)talloc_append_blob(NULL, val, *blob);
176 if (val == NULL) {
177 return false;
178 }
179
180 DEBUG(10, ("Adding cache entry with key = %s and timeout ="
181 " %s (%d seconds %s)\n", keystr, ctime(&timeout),
182 (int)(timeout - time(NULL)),
183 timeout > time(NULL) ? "ahead" : "in the past"));
184
185 ret = tdb_store_bystring(
186 cache_notrans, keystr,
187 make_tdb_data((uint8_t *)val, talloc_array_length(val)),
188 0);
189 TALLOC_FREE(val);
190
191 if (ret != 0) {
192 return false;
193 }
194
195 /*
196 * Every 100 writes within a single process, stabilize the cache with
197 * a transaction. This is done to prevent a single transaction to
198 * become huge and chew lots of memory.
199 */
200 writecount += 1;
201 if (writecount > lp_parm_int(-1, "gencache", "stabilize_count", 100)) {
202 gencache_stabilize();
203 writecount = 0;
204 goto done;
205 }
206
207 /*
208 * Every 5 minutes, call gencache_stabilize() to not let grow
209 * gencache_notrans.tdb too large.
210 */
211
212 last_stabilize = 0;
213 databuf = tdb_fetch(cache_notrans, last_stabilize_key());
214 if ((databuf.dptr != NULL)
215 && (databuf.dptr[databuf.dsize-1] == '\0')) {
216 last_stabilize = atoi((char *)databuf.dptr);
217 SAFE_FREE(databuf.dptr);
218 }
219 if ((last_stabilize
220 + lp_parm_int(-1, "gencache", "stabilize_interval", 300))
221 < time(NULL)) {
222 gencache_stabilize();
223 }
224
225done:
226 return ret == 0;
227}
228
229/**
230 * Delete one entry from the cache file.
231 *
232 * @param keystr string that represents a key of this entry
233 *
234 * @retval true upon successful deletion
235 * @retval false in case of failure
236 **/
237
238bool gencache_del(const char *keystr)
239{
240 bool exists, was_expired;
241 bool ret = false;
242 DATA_BLOB value;
243
244 if (keystr == NULL) {
245 return false;
246 }
247
248 if (!gencache_init()) return False;
249
250 DEBUG(10, ("Deleting cache entry (key = %s)\n", keystr));
251
252 /*
253 * We delete an element by setting its timeout to 0. This way we don't
254 * have to do a transaction on gencache.tdb every time we delete an
255 * element.
256 */
257
258 exists = gencache_get_data_blob(keystr, &value, NULL, &was_expired);
259
260 if (!exists && was_expired) {
261 /*
262 * gencache_get_data_blob has implicitly deleted this
263 * entry, so we have to return success here.
264 */
265 return true;
266 }
267
268 if (exists) {
269 data_blob_free(&value);
270 ret = gencache_set(keystr, "", 0);
271 }
272 return ret;
273}
274
275static bool gencache_pull_timeout(char *val, time_t *pres, char **pendptr)
276{
277 time_t res;
278 char *endptr;
279
280 if (val == NULL) {
281 return false;
282 }
283
284 res = strtol(val, &endptr, 10);
285
286 if ((endptr == NULL) || (*endptr != '/')) {
287 DEBUG(2, ("Invalid gencache data format: %s\n", val));
288 return false;
289 }
290 if (pres != NULL) {
291 *pres = res;
292 }
293 if (pendptr != NULL) {
294 *pendptr = endptr;
295 }
296 return true;
297}
298
299struct gencache_parse_state {
300 void (*parser)(time_t timeout, DATA_BLOB blob, void *private_data);
301 void *private_data;
302};
303
304static int gencache_parse_fn(TDB_DATA key, TDB_DATA data, void *private_data)
305{
306 struct gencache_parse_state *state;
307 DATA_BLOB blob;
308 time_t t;
309 char *endptr;
310 bool ret;
311
312 if (data.dptr == NULL) {
313 return -1;
314 }
315 ret = gencache_pull_timeout((char *)data.dptr, &t, &endptr);
316 if (!ret) {
317 return -1;
318 }
319 state = (struct gencache_parse_state *)private_data;
320 blob = data_blob_const(
321 endptr+1, data.dsize - PTR_DIFF(endptr+1, data.dptr));
322 state->parser(t, blob, state->private_data);
323 return 0;
324}
325
326bool gencache_parse(const char *keystr,
327 void (*parser)(time_t timeout, DATA_BLOB blob,
328 void *private_data),
329 void *private_data)
330{
331 struct gencache_parse_state state;
332 TDB_DATA key;
333 int ret;
334
335 if (keystr == NULL) {
336 return false;
337 }
338 if (tdb_data_cmp(string_term_tdb_data(keystr),
339 last_stabilize_key()) == 0) {
340 return false;
341 }
342 if (!gencache_init()) {
343 return false;
344 }
345
346 key = string_term_tdb_data(keystr);
347 state.parser = parser;
348 state.private_data = private_data;
349
350 ret = tdb_parse_record(cache_notrans, key, gencache_parse_fn, &state);
351 if (ret != -1) {
352 return true;
353 }
354 ret = tdb_parse_record(cache, key, gencache_parse_fn, &state);
355 return (ret != -1);
356}
357
358struct gencache_get_data_blob_state {
359 DATA_BLOB *blob;
360 time_t timeout;
361 bool result;
362};
363
364static void gencache_get_data_blob_parser(time_t timeout, DATA_BLOB blob,
365 void *private_data)
366{
367 struct gencache_get_data_blob_state *state =
368 (struct gencache_get_data_blob_state *)private_data;
369
370 if (timeout == 0) {
371 state->result = false;
372 return;
373 }
374 state->timeout = timeout;
375
376 if (state->blob == NULL) {
377 state->result = true;
378 return;
379 }
380
381 *state->blob = data_blob(blob.data, blob.length);
382 if (state->blob->data == NULL) {
383 state->result = false;
384 return;
385 }
386 state->result = true;
387}
388
389/**
390 * Get existing entry from the cache file.
391 *
392 * @param keystr string that represents a key of this entry
393 * @param blob DATA_BLOB that is filled with entry's blob
394 * @param timeout pointer to a time_t that is filled with entry's
395 * timeout
396 *
397 * @retval true when entry is successfuly fetched
398 * @retval False for failure
399 **/
400
401bool gencache_get_data_blob(const char *keystr, DATA_BLOB *blob,
402 time_t *timeout, bool *was_expired)
403{
404 struct gencache_get_data_blob_state state;
405 bool expired = false;
406
407 state.result = false;
408 state.blob = blob;
409
410 if (!gencache_parse(keystr, gencache_get_data_blob_parser, &state)) {
411 goto fail;
412 }
413 if (!state.result) {
414 goto fail;
415 }
416 if (state.timeout <= time(NULL)) {
417 /*
418 * We're expired, delete the entry. We can't use gencache_del
419 * here, because that uses gencache_get_data_blob for checking
420 * the existence of a record. We know the thing exists and
421 * directly store an empty value with 0 timeout.
422 */
423 gencache_set(keystr, "", 0);
424 expired = true;
425 goto fail;
426 }
427 if (timeout) {
428 *timeout = state.timeout;
429 }
430
431 return True;
432
433fail:
434 if (was_expired != NULL) {
435 *was_expired = expired;
436 }
437 if (state.result && state.blob) {
438 data_blob_free(state.blob);
439 }
440 return false;
441}
442
443struct stabilize_state {
444 bool written;
445 bool error;
446};
447static int stabilize_fn(struct tdb_context *tdb, TDB_DATA key, TDB_DATA val,
448 void *priv);
449
450/**
451 * Stabilize gencache
452 *
453 * Migrate the clear-if-first gencache data to the stable,
454 * transaction-based gencache.tdb
455 */
456
457bool gencache_stabilize(void)
458{
459 struct stabilize_state state;
460 int res;
461 char *now;
462
463 if (!gencache_init()) {
464 return false;
465 }
466
467 res = tdb_transaction_start_nonblock(cache);
468 if (res == -1) {
469
470 if (tdb_error(cache) == TDB_ERR_NOLOCK) {
471 /*
472 * Someone else already does the stabilize,
473 * this does not have to be done twice
474 */
475 return true;
476 }
477
478 DEBUG(10, ("Could not start transaction on gencache.tdb: "
479 "%s\n", tdb_errorstr(cache)));
480 return false;
481 }
482 res = tdb_transaction_start(cache_notrans);
483 if (res == -1) {
484 tdb_transaction_cancel(cache);
485 DEBUG(10, ("Could not start transaction on "
486 "gencache_notrans.tdb: %s\n",
487 tdb_errorstr(cache_notrans)));
488 return false;
489 }
490
491 state.error = false;
492 state.written = false;
493
494 res = tdb_traverse(cache_notrans, stabilize_fn, &state);
495 if ((res == -1) || state.error) {
496 if ((tdb_transaction_cancel(cache_notrans) == -1)
497 || (tdb_transaction_cancel(cache) == -1)) {
498 smb_panic("tdb_transaction_cancel failed\n");
499 }
500 return false;
501 }
502
503 if (!state.written) {
504 if ((tdb_transaction_cancel(cache_notrans) == -1)
505 || (tdb_transaction_cancel(cache) == -1)) {
506 smb_panic("tdb_transaction_cancel failed\n");
507 }
508 return true;
509 }
510
511 res = tdb_transaction_commit(cache);
512 if (res == -1) {
513 DEBUG(10, ("tdb_transaction_commit on gencache.tdb failed: "
514 "%s\n", tdb_errorstr(cache)));
515 if (tdb_transaction_cancel(cache_notrans) == -1) {
516 smb_panic("tdb_transaction_cancel failed\n");
517 }
518 return false;
519 }
520
521 res = tdb_transaction_commit(cache_notrans);
522 if (res == -1) {
523 DEBUG(10, ("tdb_transaction_commit on gencache.tdb failed: "
524 "%s\n", tdb_errorstr(cache)));
525 return false;
526 }
527
528 now = talloc_asprintf(talloc_tos(), "%d", (int)time(NULL));
529 if (now != NULL) {
530 tdb_store(cache_notrans, last_stabilize_key(),
531 string_term_tdb_data(now), 0);
532 TALLOC_FREE(now);
533 }
534
535 return true;
536}
537
538static int stabilize_fn(struct tdb_context *tdb, TDB_DATA key, TDB_DATA val,
539 void *priv)
540{
541 struct stabilize_state *state = (struct stabilize_state *)priv;
542 int res;
543 time_t timeout;
544
545 if (tdb_data_cmp(key, last_stabilize_key()) == 0) {
546 return 0;
547 }
548
549 if (!gencache_pull_timeout((char *)val.dptr, &timeout, NULL)) {
550 DEBUG(10, ("Ignoring invalid entry\n"));
551 return 0;
552 }
553 if ((timeout < time(NULL)) || (val.dsize == 0)) {
554 res = tdb_delete(cache, key);
555 if ((res == -1) && (tdb_error(cache) == TDB_ERR_NOEXIST)) {
556 res = 0;
557 } else {
558 state->written = true;
559 }
560 } else {
561 res = tdb_store(cache, key, val, 0);
562 if (res == 0) {
563 state->written = true;
564 }
565 }
566
567 if (res == -1) {
568 DEBUG(10, ("Transfer to gencache.tdb failed: %s\n",
569 tdb_errorstr(cache)));
570 state->error = true;
571 return -1;
572 }
573
574 if (tdb_delete(cache_notrans, key) == -1) {
575 DEBUG(10, ("tdb_delete from gencache_notrans.tdb failed: "
576 "%s\n", tdb_errorstr(cache_notrans)));
577 state->error = true;
578 return -1;
579 }
580 return 0;
581}
582
583/**
584 * Get existing entry from the cache file.
585 *
586 * @param keystr string that represents a key of this entry
587 * @param valstr buffer that is allocated and filled with the entry value
588 * buffer's disposing must be done outside
589 * @param timeout pointer to a time_t that is filled with entry's
590 * timeout
591 *
592 * @retval true when entry is successfuly fetched
593 * @retval False for failure
594 **/
595
596bool gencache_get(const char *keystr, char **value, time_t *ptimeout)
597{
598 DATA_BLOB blob;
599 bool ret = False;
600
601 ret = gencache_get_data_blob(keystr, &blob, ptimeout, NULL);
602 if (!ret) {
603 return false;
604 }
605 if ((blob.data == NULL) || (blob.length == 0)) {
606 SAFE_FREE(blob.data);
607 return false;
608 }
609 if (blob.data[blob.length-1] != '\0') {
610 /* Not NULL terminated, can't be a string */
611 SAFE_FREE(blob.data);
612 return false;
613 }
614 if (value) {
615 *value = SMB_STRDUP((char *)blob.data);
616 data_blob_free(&blob);
617 if (*value == NULL) {
618 return false;
619 }
620 return true;
621 }
622 data_blob_free(&blob);
623 return true;
624}
625
626/**
627 * Set an entry in the cache file. If there's no such
628 * one, then add it.
629 *
630 * @param keystr string that represents a key of this entry
631 * @param value text representation value being cached
632 * @param timeout time when the value is expired
633 *
634 * @retval true when entry is successfuly stored
635 * @retval false on failure
636 **/
637
638bool gencache_set(const char *keystr, const char *value, time_t timeout)
639{
640 DATA_BLOB blob = data_blob_const(value, strlen(value)+1);
641 return gencache_set_data_blob(keystr, &blob, timeout);
642}
643
644struct gencache_iterate_blobs_state {
645 void (*fn)(const char *key, DATA_BLOB value,
646 time_t timeout, void *private_data);
647 const char *pattern;
648 void *private_data;
649 bool in_persistent;
650};
651
652static int gencache_iterate_blobs_fn(struct tdb_context *tdb, TDB_DATA key,
653 TDB_DATA data, void *priv)
654{
655 struct gencache_iterate_blobs_state *state =
656 (struct gencache_iterate_blobs_state *)priv;
657 char *keystr;
658 char *free_key = NULL;
659 time_t timeout;
660 char *endptr;
661
662 if (tdb_data_cmp(key, last_stabilize_key()) == 0) {
663 return 0;
664 }
665 if (state->in_persistent && tdb_exists(cache_notrans, key)) {
666 return 0;
667 }
668
669 if (key.dptr[key.dsize-1] == '\0') {
670 keystr = (char *)key.dptr;
671 } else {
672 /* ensure 0-termination */
673 keystr = SMB_STRNDUP((char *)key.dptr, key.dsize);
674 free_key = keystr;
675 }
676
677 if (!gencache_pull_timeout((char *)data.dptr, &timeout, &endptr)) {
678 goto done;
679 }
680 endptr += 1;
681
682 if (fnmatch(state->pattern, keystr, 0) != 0) {
683 goto done;
684 }
685
686 DEBUG(10, ("Calling function with arguments (key=%s, timeout=%s)\n",
687 keystr, ctime(&timeout)));
688
689 state->fn(keystr,
690 data_blob_const(endptr,
691 data.dsize - PTR_DIFF(endptr, data.dptr)),
692 timeout, state->private_data);
693
694 done:
695 SAFE_FREE(free_key);
696 return 0;
697}
698
699void gencache_iterate_blobs(void (*fn)(const char *key, DATA_BLOB value,
700 time_t timeout, void *private_data),
701 void *private_data, const char *pattern)
702{
703 struct gencache_iterate_blobs_state state;
704
705 if ((fn == NULL) || (pattern == NULL) || !gencache_init()) {
706 return;
707 }
708
709 DEBUG(5, ("Searching cache keys with pattern %s\n", pattern));
710
711 state.fn = fn;
712 state.pattern = pattern;
713 state.private_data = private_data;
714
715 state.in_persistent = false;
716 tdb_traverse(cache_notrans, gencache_iterate_blobs_fn, &state);
717
718 state.in_persistent = true;
719 tdb_traverse(cache, gencache_iterate_blobs_fn, &state);
720}
721
722/**
723 * Iterate through all entries which key matches to specified pattern
724 *
725 * @param fn pointer to the function that will be supplied with each single
726 * matching cache entry (key, value and timeout) as an arguments
727 * @param data void pointer to an arbitrary data that is passed directly to the fn
728 * function on each call
729 * @param keystr_pattern pattern the existing entries' keys are matched to
730 *
731 **/
732
733struct gencache_iterate_state {
734 void (*fn)(const char *key, const char *value, time_t timeout,
735 void *priv);
736 void *private_data;
737};
738
739static void gencache_iterate_fn(const char *key, DATA_BLOB value,
740 time_t timeout, void *private_data)
741{
742 struct gencache_iterate_state *state =
743 (struct gencache_iterate_state *)private_data;
744 char *valstr;
745 char *free_val = NULL;
746
747 if (value.data[value.length-1] == '\0') {
748 valstr = (char *)value.data;
749 } else {
750 /* ensure 0-termination */
751 valstr = SMB_STRNDUP((char *)value.data, value.length);
752 free_val = valstr;
753 }
754
755 DEBUG(10, ("Calling function with arguments "
756 "(key = %s, value = %s, timeout = %s)\n",
757 key, valstr, ctime(&timeout)));
758
759 state->fn(key, valstr, timeout, state->private_data);
760
761 SAFE_FREE(free_val);
762}
763
764void gencache_iterate(void (*fn)(const char *key, const char *value,
765 time_t timeout, void *dptr),
766 void *private_data, const char *pattern)
767{
768 struct gencache_iterate_state state;
769
770 if (fn == NULL) {
771 return;
772 }
773 state.fn = fn;
774 state.private_data = private_data;
775 gencache_iterate_blobs(gencache_iterate_fn, &state, pattern);
776}
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