source: trunk/server/source3/lib/gencache.c@ 533

Last change on this file since 533 was 414, checked in by Herwig Bauernfeind, 16 years ago

Samba 3.5.0: Initial import
File size: 15.8 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
26#undef DBGC_CLASS
27#define DBGC_CLASS DBGC_TDB
28
29#define TIMEOUT_LEN 12
30#define CACHE_DATA_FMT "%12u/"
31#define READ_CACHE_DATA_FMT_TEMPLATE "%%12u/%%%us"
32#define BLOB_TYPE "DATA_BLOB"
33#define BLOB_TYPE_LEN 9
34
35static struct tdb_context *cache;
36static struct tdb_context *cache_notrans;
37
38/**
39 * @file gencache.c
40 * @brief Generic, persistent and shared between processes cache mechanism
41 * for use by various parts of the Samba code
42 *
43 **/
44
45
46/**
47 * Cache initialisation function. Opens cache tdb file or creates
48 * it if does not exist.
49 *
50 * @return true on successful initialisation of the cache or
51 * false on failure
52 **/
53
54static bool gencache_init(void)
55{
56 char* cache_fname = NULL;
57 int open_flags = O_RDWR|O_CREAT;
58 bool first_try = true;
59
60 /* skip file open if it's already opened */
61 if (cache) return True;
62
63 cache_fname = lock_path("gencache.tdb");
64
65 DEBUG(5, ("Opening cache file at %s\n", cache_fname));
66
67again:
68 cache = tdb_open_log(cache_fname, 0, TDB_DEFAULT, open_flags, 0644);
69 if (cache) {
70 int ret;
71 ret = tdb_check(cache, NULL, NULL);
72 if (ret != 0) {
73 tdb_close(cache);
74 cache = NULL;
75 if (!first_try) {
76 DEBUG(0, ("gencache_init: tdb_check(%s) failed\n",
77 cache_fname));
78 return false;
79 }
80 first_try = false;
81 DEBUG(0, ("gencache_init: tdb_check(%s) failed - retry after CLEAR_IF_FIRST\n",
82 cache_fname));
83 cache = tdb_open_log(cache_fname, 0, TDB_CLEAR_IF_FIRST, open_flags, 0644);
84 if (cache) {
85 tdb_close(cache);
86 cache = NULL;
87 goto again;
88 }
89 }
90 }
91
92 if (!cache && (errno == EACCES)) {
93 open_flags = O_RDONLY;
94 cache = tdb_open_log(cache_fname, 0, TDB_DEFAULT, open_flags,
95 0644);
96 if (cache) {
97 DEBUG(5, ("gencache_init: Opening cache file %s read-only.\n", cache_fname));
98 }
99 }
100
101 if (!cache) {
102 DEBUG(5, ("Attempt to open gencache.tdb has failed.\n"));
103 return False;
104 }
105
106 cache_fname = lock_path("gencache_notrans.tdb");
107
108 DEBUG(5, ("Opening cache file at %s\n", cache_fname));
109
110 cache_notrans = tdb_open_log(cache_fname, 0, TDB_CLEAR_IF_FIRST,
111 open_flags, 0644);
112 if (cache_notrans == NULL) {
113 DEBUG(5, ("Opening %s failed: %s\n", cache_fname,
114 strerror(errno)));
115 tdb_close(cache);
116 cache = NULL;
117 return false;
118 }
119
120 return True;
121}
122
123static TDB_DATA last_stabilize_key(void)
124{
125 TDB_DATA result;
126 result.dptr = (uint8_t *)"@LAST_STABILIZED";
127 result.dsize = 17;
128 return result;
129}
130
131/**
132 * Set an entry in the cache file. If there's no such
133 * one, then add it.
134 *
135 * @param keystr string that represents a key of this entry
136 * @param blob DATA_BLOB value being cached
137 * @param timeout time when the value is expired
138 *
139 * @retval true when entry is successfuly stored
140 * @retval false on failure
141 **/
142
143bool gencache_set_data_blob(const char *keystr, const DATA_BLOB *blob,
144 time_t timeout)
145{
146 int ret;
147 TDB_DATA databuf;
148 char* val;
149 time_t last_stabilize;
150 static int writecount;
151
152 if (tdb_data_cmp(string_term_tdb_data(keystr),
153 last_stabilize_key()) == 0) {
154 DEBUG(10, ("Can't store %s as a key\n", keystr));
155 return false;
156 }
157
158 if ((keystr == NULL) || (blob == NULL)) {
159 return false;
160 }
161
162 if (!gencache_init()) return False;
163
164 val = talloc_asprintf(talloc_tos(), CACHE_DATA_FMT, (int)timeout);
165 if (val == NULL) {
166 return False;
167 }
168 val = talloc_realloc(NULL, val, char, talloc_array_length(val)-1);
169 if (val == NULL) {
170 return false;
171 }
172 val = (char *)talloc_append_blob(NULL, val, *blob);
173 if (val == NULL) {
174 return false;
175 }
176
177 DEBUG(10, ("Adding cache entry with key = %s and timeout ="
178 " %s (%d seconds %s)\n", keystr, ctime(&timeout),
179 (int)(timeout - time(NULL)),
180 timeout > time(NULL) ? "ahead" : "in the past"));
181
182 ret = tdb_store_bystring(
183 cache_notrans, keystr,
184 make_tdb_data((uint8_t *)val, talloc_array_length(val)),
185 0);
186 TALLOC_FREE(val);
187
188 if (ret != 0) {
189 return false;
190 }
191
192 /*
193 * Every 100 writes within a single process, stabilize the cache with
194 * a transaction. This is done to prevent a single transaction to
195 * become huge and chew lots of memory.
196 */
197 writecount += 1;
198 if (writecount > lp_parm_int(-1, "gencache", "stabilize_count", 100)) {
199 gencache_stabilize();
200 writecount = 0;
201 goto done;
202 }
203
204 /*
205 * Every 5 minutes, call gencache_stabilize() to not let grow
206 * gencache_notrans.tdb too large.
207 */
208
209 last_stabilize = 0;
210 databuf = tdb_fetch(cache_notrans, last_stabilize_key());
211 if ((databuf.dptr != NULL)
212 && (databuf.dptr[databuf.dsize-1] == '\0')) {
213 last_stabilize = atoi((char *)databuf.dptr);
214 SAFE_FREE(databuf.dptr);
215 }
216 if ((last_stabilize
217 + lp_parm_int(-1, "gencache", "stabilize_interval", 300))
218 < time(NULL)) {
219 gencache_stabilize();
220 }
221
222done:
223 return ret == 0;
224}
225
226/**
227 * Delete one entry from the cache file.
228 *
229 * @param keystr string that represents a key of this entry
230 *
231 * @retval true upon successful deletion
232 * @retval false in case of failure
233 **/
234
235bool gencache_del(const char *keystr)
236{
237 bool exists, was_expired;
238 bool ret = false;
239 DATA_BLOB value;
240
241 if (keystr == NULL) {
242 return false;
243 }
244
245 if (!gencache_init()) return False;
246
247 DEBUG(10, ("Deleting cache entry (key = %s)\n", keystr));
248
249 /*
250 * We delete an element by setting its timeout to 0. This way we don't
251 * have to do a transaction on gencache.tdb every time we delete an
252 * element.
253 */
254
255 exists = gencache_get_data_blob(keystr, &value, NULL, &was_expired);
256
257 if (!exists && was_expired) {
258 /*
259 * gencache_get_data_blob has implicitly deleted this
260 * entry, so we have to return success here.
261 */
262 return true;
263 }
264
265 if (exists) {
266 data_blob_free(&value);
267 ret = gencache_set(keystr, "", 0);
268 }
269 return ret;
270}
271
272static bool gencache_pull_timeout(char *val, time_t *pres, char **pendptr)
273{
274 time_t res;
275 char *endptr;
276
277 res = strtol(val, &endptr, 10);
278
279 if ((endptr == NULL) || (*endptr != '/')) {
280 DEBUG(2, ("Invalid gencache data format: %s\n", val));
281 return false;
282 }
283 if (pres != NULL) {
284 *pres = res;
285 }
286 if (pendptr != NULL) {
287 *pendptr = endptr;
288 }
289 return true;
290}
291
292/**
293 * Get existing entry from the cache file.
294 *
295 * @param keystr string that represents a key of this entry
296 * @param blob DATA_BLOB that is filled with entry's blob
297 * @param timeout pointer to a time_t that is filled with entry's
298 * timeout
299 *
300 * @retval true when entry is successfuly fetched
301 * @retval False for failure
302 **/
303
304bool gencache_get_data_blob(const char *keystr, DATA_BLOB *blob,
305 time_t *timeout, bool *was_expired)
306{
307 TDB_DATA databuf;
308 time_t t;
309 char *endptr;
310 bool expired = false;
311
312 if (keystr == NULL) {
313 goto fail;
314 }
315
316 if (tdb_data_cmp(string_term_tdb_data(keystr),
317 last_stabilize_key()) == 0) {
318 DEBUG(10, ("Can't get %s as a key\n", keystr));
319 goto fail;
320 }
321
322 if (!gencache_init()) {
323 goto fail;
324 }
325
326 databuf = tdb_fetch_bystring(cache_notrans, keystr);
327
328 if (databuf.dptr == NULL) {
329 databuf = tdb_fetch_bystring(cache, keystr);
330 }
331
332 if (databuf.dptr == NULL) {
333 DEBUG(10, ("Cache entry with key = %s couldn't be found \n",
334 keystr));
335 goto fail;
336 }
337
338 if (!gencache_pull_timeout((char *)databuf.dptr, &t, &endptr)) {
339 SAFE_FREE(databuf.dptr);
340 goto fail;
341 }
342
343 DEBUG(10, ("Returning %s cache entry: key = %s, value = %s, "
344 "timeout = %s", t > time(NULL) ? "valid" :
345 "expired", keystr, endptr+1, ctime(&t)));
346
347 if (t == 0) {
348 /* Deleted */
349 SAFE_FREE(databuf.dptr);
350 goto fail;
351 }
352
353 if (t <= time(NULL)) {
354
355 /*
356 * We're expired, delete the entry. We can't use gencache_del
357 * here, because that uses gencache_get_data_blob for checking
358 * the existence of a record. We know the thing exists and
359 * directly store an empty value with 0 timeout.
360 */
361 gencache_set(keystr, "", 0);
362
363 SAFE_FREE(databuf.dptr);
364
365 expired = true;
366 goto fail;
367 }
368
369 if (blob != NULL) {
370 *blob = data_blob(
371 endptr+1,
372 databuf.dsize - PTR_DIFF(endptr+1, databuf.dptr));
373 if (blob->data == NULL) {
374 SAFE_FREE(databuf.dptr);
375 DEBUG(0, ("memdup failed\n"));
376 goto fail;
377 }
378 }
379
380 SAFE_FREE(databuf.dptr);
381
382 if (timeout) {
383 *timeout = t;
384 }
385
386 return True;
387
388fail:
389 if (was_expired != NULL) {
390 *was_expired = expired;
391 }
392 return false;
393}
394
395struct stabilize_state {
396 bool written;
397 bool error;
398};
399static int stabilize_fn(struct tdb_context *tdb, TDB_DATA key, TDB_DATA val,
400 void *priv);
401
402/**
403 * Stabilize gencache
404 *
405 * Migrate the clear-if-first gencache data to the stable,
406 * transaction-based gencache.tdb
407 */
408
409bool gencache_stabilize(void)
410{
411 struct stabilize_state state;
412 int res;
413 char *now;
414
415 if (!gencache_init()) {
416 return false;
417 }
418
419 res = tdb_transaction_start(cache);
420 if (res == -1) {
421 DEBUG(10, ("Could not start transaction on gencache.tdb: "
422 "%s\n", tdb_errorstr(cache)));
423 return false;
424 }
425 res = tdb_transaction_start(cache_notrans);
426 if (res == -1) {
427 tdb_transaction_cancel(cache);
428 DEBUG(10, ("Could not start transaction on "
429 "gencache_notrans.tdb: %s\n",
430 tdb_errorstr(cache_notrans)));
431 return false;
432 }
433
434 state.error = false;
435 state.written = false;
436
437 res = tdb_traverse(cache_notrans, stabilize_fn, &state);
438 if ((res == -1) || state.error) {
439 if ((tdb_transaction_cancel(cache_notrans) == -1)
440 || (tdb_transaction_cancel(cache) == -1)) {
441 smb_panic("tdb_transaction_cancel failed\n");
442 }
443 return false;
444 }
445
446 if (!state.written) {
447 if ((tdb_transaction_cancel(cache_notrans) == -1)
448 || (tdb_transaction_cancel(cache) == -1)) {
449 smb_panic("tdb_transaction_cancel failed\n");
450 }
451 return true;
452 }
453
454 res = tdb_transaction_commit(cache);
455 if (res == -1) {
456 DEBUG(10, ("tdb_transaction_commit on gencache.tdb failed: "
457 "%s\n", tdb_errorstr(cache)));
458 if (tdb_transaction_cancel(cache_notrans) == -1) {
459 smb_panic("tdb_transaction_cancel failed\n");
460 }
461 return false;
462 }
463
464 res = tdb_transaction_commit(cache_notrans);
465 if (res == -1) {
466 DEBUG(10, ("tdb_transaction_commit on gencache.tdb failed: "
467 "%s\n", tdb_errorstr(cache)));
468 return false;
469 }
470
471 now = talloc_asprintf(talloc_tos(), "%d", (int)time(NULL));
472 if (now != NULL) {
473 tdb_store(cache_notrans, last_stabilize_key(),
474 string_term_tdb_data(now), 0);
475 TALLOC_FREE(now);
476 }
477
478 return true;
479}
480
481static int stabilize_fn(struct tdb_context *tdb, TDB_DATA key, TDB_DATA val,
482 void *priv)
483{
484 struct stabilize_state *state = (struct stabilize_state *)priv;
485 int res;
486 time_t timeout;
487
488 if (tdb_data_cmp(key, last_stabilize_key()) == 0) {
489 return 0;
490 }
491
492 if (!gencache_pull_timeout((char *)val.dptr, &timeout, NULL)) {
493 DEBUG(10, ("Ignoring invalid entry\n"));
494 return 0;
495 }
496 if ((timeout < time(NULL)) || (val.dsize == 0)) {
497 res = tdb_delete(cache, key);
498 if ((res == -1) && (tdb_error(cache) == TDB_ERR_NOEXIST)) {
499 res = 0;
500 } else {
501 state->written = true;
502 }
503 } else {
504 res = tdb_store(cache, key, val, 0);
505 if (res == 0) {
506 state->written = true;
507 }
508 }
509
510 if (res == -1) {
511 DEBUG(10, ("Transfer to gencache.tdb failed: %s\n",
512 tdb_errorstr(cache)));
513 state->error = true;
514 return -1;
515 }
516
517 if (tdb_delete(cache_notrans, key) == -1) {
518 DEBUG(10, ("tdb_delete from gencache_notrans.tdb failed: "
519 "%s\n", tdb_errorstr(cache_notrans)));
520 state->error = true;
521 return -1;
522 }
523 return 0;
524}
525
526/**
527 * Get existing entry from the cache file.
528 *
529 * @param keystr string that represents a key of this entry
530 * @param valstr buffer that is allocated and filled with the entry value
531 * buffer's disposing must be done outside
532 * @param timeout pointer to a time_t that is filled with entry's
533 * timeout
534 *
535 * @retval true when entry is successfuly fetched
536 * @retval False for failure
537 **/
538
539bool gencache_get(const char *keystr, char **value, time_t *ptimeout)
540{
541 DATA_BLOB blob;
542 bool ret = False;
543
544 ret = gencache_get_data_blob(keystr, &blob, ptimeout, NULL);
545 if (!ret) {
546 return false;
547 }
548 if ((blob.data == NULL) || (blob.length == 0)) {
549 SAFE_FREE(blob.data);
550 return false;
551 }
552 if (blob.data[blob.length-1] != '\0') {
553 /* Not NULL terminated, can't be a string */
554 SAFE_FREE(blob.data);
555 return false;
556 }
557 if (value) {
558 *value = SMB_STRDUP((char *)blob.data);
559 data_blob_free(&blob);
560 if (*value == NULL) {
561 return false;
562 }
563 return true;
564 }
565 data_blob_free(&blob);
566 return true;
567}
568
569/**
570 * Set an entry in the cache file. If there's no such
571 * one, then add it.
572 *
573 * @param keystr string that represents a key of this entry
574 * @param value text representation value being cached
575 * @param timeout time when the value is expired
576 *
577 * @retval true when entry is successfuly stored
578 * @retval false on failure
579 **/
580
581bool gencache_set(const char *keystr, const char *value, time_t timeout)
582{
583 DATA_BLOB blob = data_blob_const(value, strlen(value)+1);
584 return gencache_set_data_blob(keystr, &blob, timeout);
585}
586
587/**
588 * Iterate through all entries which key matches to specified pattern
589 *
590 * @param fn pointer to the function that will be supplied with each single
591 * matching cache entry (key, value and timeout) as an arguments
592 * @param data void pointer to an arbitrary data that is passed directly to the fn
593 * function on each call
594 * @param keystr_pattern pattern the existing entries' keys are matched to
595 *
596 **/
597
598struct gencache_iterate_state {
599 void (*fn)(const char *key, const char *value, time_t timeout,
600 void *priv);
601 const char *pattern;
602 void *priv;
603 bool in_persistent;
604};
605
606static int gencache_iterate_fn(struct tdb_context *tdb, TDB_DATA key,
607 TDB_DATA value, void *priv)
608{
609 struct gencache_iterate_state *state =
610 (struct gencache_iterate_state *)priv;
611 char *keystr;
612 char *free_key = NULL;
613 char *valstr;
614 char *free_val = NULL;
615 unsigned long u;
616 time_t timeout;
617 char *timeout_endp;
618
619 if (tdb_data_cmp(key, last_stabilize_key()) == 0) {
620 return 0;
621 }
622
623 if (state->in_persistent && tdb_exists(cache_notrans, key)) {
624 return 0;
625 }
626
627 if (key.dptr[key.dsize-1] == '\0') {
628 keystr = (char *)key.dptr;
629 } else {
630 /* ensure 0-termination */
631 keystr = SMB_STRNDUP((char *)key.dptr, key.dsize);
632 free_key = keystr;
633 }
634
635 if ((value.dptr == NULL) || (value.dsize <= TIMEOUT_LEN)) {
636 goto done;
637 }
638
639 if (fnmatch(state->pattern, keystr, 0) != 0) {
640 goto done;
641 }
642
643 if (value.dptr[value.dsize-1] == '\0') {
644 valstr = (char *)value.dptr;
645 } else {
646 /* ensure 0-termination */
647 valstr = SMB_STRNDUP((char *)value.dptr, value.dsize);
648 free_val = valstr;
649 }
650
651 u = strtoul(valstr, &timeout_endp, 10);
652
653 if ((*timeout_endp != '/') || ((timeout_endp-valstr) != TIMEOUT_LEN)) {
654 goto done;
655 }
656
657 timeout = u;
658 timeout_endp += 1;
659
660 DEBUG(10, ("Calling function with arguments "
661 "(key = %s, value = %s, timeout = %s)\n",
662 keystr, timeout_endp, ctime(&timeout)));
663 state->fn(keystr, timeout_endp, timeout, state->priv);
664
665 done:
666 SAFE_FREE(free_key);
667 SAFE_FREE(free_val);
668 return 0;
669}
670
671void gencache_iterate(void (*fn)(const char* key, const char *value, time_t timeout, void* dptr),
672 void* data, const char* keystr_pattern)
673{
674 struct gencache_iterate_state state;
675
676 if ((fn == NULL) || (keystr_pattern == NULL)) {
677 return;
678 }
679
680 if (!gencache_init()) return;
681
682 DEBUG(5, ("Searching cache keys with pattern %s\n", keystr_pattern));
683
684 state.fn = fn;
685 state.pattern = keystr_pattern;
686 state.priv = data;
687
688 state.in_persistent = false;
689 tdb_traverse(cache_notrans, gencache_iterate_fn, &state);
690
691 state.in_persistent = true;
692 tdb_traverse(cache, gencache_iterate_fn, &state);
693}
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