1 /* Licensed to the Apache Software Foundation (ASF) under one or more
2 * contributor license agreements. See the NOTICE file distributed with
3 * this work for additional information regarding copyright ownership.
4 * The ASF licenses this file to You under the Apache License, Version 2.0
5 * (the "License"); you may not use this file except in compliance with
6 * the License. You may obtain a copy of the License at
7 *
8 * http://www.apache.org/licenses/LICENSE-2.0
9 *
10 * Unless required by applicable law or agreed to in writing, software
11 * distributed under the License is distributed on an "AS IS" BASIS,
12 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
13 * See the License for the specific language governing permissions and
14 * limitations under the License.
15 */
16
17 /*
18 * sdbm - ndbm work-alike hashed database library
19 * based on Per-Aake Larson's Dynamic Hashing algorithms. BIT 18 (1978).
20 * author: oz@nexus.yorku.ca
21 * ex-public domain, ported to APR for Apache 2
22 * core routines
23 */
24
25 #include "apr.h"
26 #include "apr_file_io.h"
27 #include "apr_strings.h"
28 #include "apr_errno.h"
29 #include "apr_sdbm.h"
30
31 #include "sdbm_tune.h"
32 #include "sdbm_pair.h"
33 #include "sdbm_private.h"
34
35 #include <string.h> /* for memset() */
36 #include <stdlib.h> /* for malloc() and free() */
37
38 /*
39 * forward
40 */
41 static int getdbit (apr_sdbm_t *, long);
42 static apr_status_t setdbit(apr_sdbm_t *, long);
43 static apr_status_t getpage(apr_sdbm_t *db, long, int, int);
44 static apr_status_t getnext(apr_sdbm_datum_t *key, apr_sdbm_t *db);
45 static apr_status_t makroom(apr_sdbm_t *, long, int);
46
47 /*
48 * useful macros
49 */
50 #define bad(x) ((x).dptr == NULL || (x).dsize <= 0)
51 #define exhash(item) sdbm_hash((item).dptr, (item).dsize)
52
53 #define OFF_PAG(off) (apr_off_t) (off) * PBLKSIZ
54 #define OFF_DIR(off) (apr_off_t) (off) * DBLKSIZ
55
56 static const long masks[] = {
57 000000000000, 000000000001, 000000000003, 000000000007,
58 000000000017, 000000000037, 000000000077, 000000000177,
59 000000000377, 000000000777, 000000001777, 000000003777,
60 000000007777, 000000017777, 000000037777, 000000077777,
61 000000177777, 000000377777, 000000777777, 000001777777,
62 000003777777, 000007777777, 000017777777, 000037777777,
63 000077777777, 000177777777, 000377777777, 000777777777,
64 001777777777, 003777777777, 007777777777, 017777777777
65 };
66
67 const apr_sdbm_datum_t sdbm_nullitem = { NULL, 0 };
68
database_cleanup(void * data)69 static apr_status_t database_cleanup(void *data)
70 {
71 apr_sdbm_t *db = data;
72
73 /*
74 * Can't rely on apr_sdbm_unlock, since it will merely
75 * decrement the refcnt if several locks are held.
76 */
77 if (db->flags & (SDBM_SHARED_LOCK | SDBM_EXCLUSIVE_LOCK))
78 (void) apr_file_unlock(db->dirf);
79 (void) apr_file_close(db->dirf);
80 (void) apr_file_close(db->pagf);
81 free(db);
82
83 return APR_SUCCESS;
84 }
85
prep(apr_sdbm_t ** pdb,const char * dirname,const char * pagname,apr_int32_t flags,apr_fileperms_t perms,apr_pool_t * p)86 static apr_status_t prep(apr_sdbm_t **pdb, const char *dirname, const char *pagname,
87 apr_int32_t flags, apr_fileperms_t perms, apr_pool_t *p)
88 {
89 apr_sdbm_t *db;
90 apr_status_t status;
91
92 *pdb = NULL;
93
94 db = malloc(sizeof(*db));
95 memset(db, 0, sizeof(*db));
96 db->pagbno = -1L;
97
98 db->pool = p;
99
100 /*
101 * adjust user flags so that WRONLY becomes RDWR,
102 * as required by this package. Also set our internal
103 * flag for RDONLY if needed.
104 */
105 if (!(flags & APR_FOPEN_WRITE)) {
106 db->flags |= SDBM_RDONLY;
107 }
108
109 /*
110 * adjust the file open flags so that we handle locking
111 * on our own (don't rely on any locking behavior within
112 * an apr_file_t, in case it's ever introduced, and set
113 * our own flag.
114 */
115 if (flags & APR_FOPEN_SHARELOCK) {
116 db->flags |= SDBM_SHARED;
117 flags &= ~APR_FOPEN_SHARELOCK;
118 }
119
120 flags |= APR_FOPEN_BINARY | APR_FOPEN_READ;
121
122 /*
123 * open the files in sequence, and stat the dirfile.
124 * If we fail anywhere, undo everything, return NULL.
125 */
126
127 if ((status = apr_file_open(&db->dirf, dirname, flags, perms, p))
128 != APR_SUCCESS)
129 goto error;
130
131 if ((status = apr_file_open(&db->pagf, pagname, flags, perms, p))
132 != APR_SUCCESS)
133 goto error;
134
135 if ((status = apr_sdbm_lock(db, (db->flags & SDBM_RDONLY)
136 ? APR_FLOCK_SHARED
137 : APR_FLOCK_EXCLUSIVE))
138 != APR_SUCCESS)
139 goto error;
140
141 /* apr_pcalloc zeroed the buffers
142 * apr_sdbm_lock stated the dirf->size and invalidated the cache
143 */
144
145 /*
146 * if we are opened in SHARED mode, unlock ourself
147 */
148 if (db->flags & SDBM_SHARED)
149 if ((status = apr_sdbm_unlock(db)) != APR_SUCCESS)
150 goto error;
151
152 /* make sure that we close the database at some point */
153 apr_pool_cleanup_register(p, db, database_cleanup, apr_pool_cleanup_null);
154
155 /* Done! */
156 *pdb = db;
157 return APR_SUCCESS;
158
159 error:
160 if (db->dirf && db->pagf)
161 (void) apr_sdbm_unlock(db);
162 if (db->dirf != NULL)
163 (void) apr_file_close(db->dirf);
164 if (db->pagf != NULL) {
165 (void) apr_file_close(db->pagf);
166 }
167 free(db);
168 return status;
169 }
170
apr_sdbm_open(apr_sdbm_t ** db,const char * file,apr_int32_t flags,apr_fileperms_t perms,apr_pool_t * p)171 APU_DECLARE(apr_status_t) apr_sdbm_open(apr_sdbm_t **db, const char *file,
172 apr_int32_t flags,
173 apr_fileperms_t perms, apr_pool_t *p)
174 {
175 char *dirname = apr_pstrcat(p, file, APR_SDBM_DIRFEXT, NULL);
176 char *pagname = apr_pstrcat(p, file, APR_SDBM_PAGFEXT, NULL);
177
178 return prep(db, dirname, pagname, flags, perms, p);
179 }
180
apr_sdbm_close(apr_sdbm_t * db)181 APU_DECLARE(apr_status_t) apr_sdbm_close(apr_sdbm_t *db)
182 {
183 return apr_pool_cleanup_run(db->pool, db, database_cleanup);
184 }
185
apr_sdbm_fetch(apr_sdbm_t * db,apr_sdbm_datum_t * val,apr_sdbm_datum_t key)186 APU_DECLARE(apr_status_t) apr_sdbm_fetch(apr_sdbm_t *db, apr_sdbm_datum_t *val,
187 apr_sdbm_datum_t key)
188 {
189 apr_status_t status;
190
191 if (db == NULL || bad(key))
192 return APR_EINVAL;
193
194 if ((status = apr_sdbm_lock(db, APR_FLOCK_SHARED)) != APR_SUCCESS)
195 return status;
196
197 if ((status = getpage(db, exhash(key), 0, 1)) == APR_SUCCESS) {
198 *val = getpair(db->pagbuf, key);
199 /* ### do we want a not-found result? */
200 }
201
202 (void) apr_sdbm_unlock(db);
203
204 return status;
205 }
206
write_page(apr_sdbm_t * db,const char * buf,long pagno)207 static apr_status_t write_page(apr_sdbm_t *db, const char *buf, long pagno)
208 {
209 apr_status_t status;
210 apr_off_t off = OFF_PAG(pagno);
211
212 if ((status = apr_file_seek(db->pagf, APR_SET, &off)) == APR_SUCCESS)
213 status = apr_file_write_full(db->pagf, buf, PBLKSIZ, NULL);
214
215 return status;
216 }
217
apr_sdbm_delete(apr_sdbm_t * db,const apr_sdbm_datum_t key)218 APU_DECLARE(apr_status_t) apr_sdbm_delete(apr_sdbm_t *db,
219 const apr_sdbm_datum_t key)
220 {
221 apr_status_t status;
222
223 if (db == NULL || bad(key))
224 return APR_EINVAL;
225 if (apr_sdbm_rdonly(db))
226 return APR_EINVAL;
227
228 if ((status = apr_sdbm_lock(db, APR_FLOCK_EXCLUSIVE)) != APR_SUCCESS)
229 return status;
230
231 if ((status = getpage(db, exhash(key), 0, 1)) == APR_SUCCESS) {
232 if (!delpair(db->pagbuf, key))
233 /* ### should we define some APRUTIL codes? */
234 status = APR_EGENERAL;
235 else
236 status = write_page(db, db->pagbuf, db->pagbno);
237 }
238
239 (void) apr_sdbm_unlock(db);
240
241 return status;
242 }
243
apr_sdbm_store(apr_sdbm_t * db,apr_sdbm_datum_t key,apr_sdbm_datum_t val,int flags)244 APU_DECLARE(apr_status_t) apr_sdbm_store(apr_sdbm_t *db, apr_sdbm_datum_t key,
245 apr_sdbm_datum_t val, int flags)
246 {
247 int need;
248 register long hash;
249 apr_status_t status;
250
251 if (db == NULL || bad(key))
252 return APR_EINVAL;
253 if (apr_sdbm_rdonly(db))
254 return APR_EINVAL;
255 need = key.dsize + val.dsize;
256 /*
257 * is the pair too big (or too small) for this database ??
258 */
259 if (need < 0 || need > PAIRMAX)
260 return APR_EINVAL;
261
262 if ((status = apr_sdbm_lock(db, APR_FLOCK_EXCLUSIVE)) != APR_SUCCESS)
263 return status;
264
265 if ((status = getpage(db, (hash = exhash(key)), 0, 1)) == APR_SUCCESS) {
266
267 /*
268 * if we need to replace, delete the key/data pair
269 * first. If it is not there, ignore.
270 */
271 if (flags == APR_SDBM_REPLACE)
272 (void) delpair(db->pagbuf, key);
273 else if (!(flags & APR_SDBM_INSERTDUP) && duppair(db->pagbuf, key)) {
274 status = APR_EEXIST;
275 goto error;
276 }
277 /*
278 * if we do not have enough room, we have to split.
279 */
280 if (!fitpair(db->pagbuf, need))
281 if ((status = makroom(db, hash, need)) != APR_SUCCESS)
282 goto error;
283 /*
284 * we have enough room or split is successful. insert the key,
285 * and update the page file.
286 */
287 (void) putpair(db->pagbuf, key, val);
288
289 status = write_page(db, db->pagbuf, db->pagbno);
290 }
291
292 error:
293 (void) apr_sdbm_unlock(db);
294
295 return status;
296 }
297
298 /*
299 * makroom - make room by splitting the overfull page
300 * this routine will attempt to make room for SPLTMAX times before
301 * giving up.
302 */
makroom(apr_sdbm_t * db,long hash,int need)303 static apr_status_t makroom(apr_sdbm_t *db, long hash, int need)
304 {
305 long newp;
306 char twin[PBLKSIZ];
307 char *pag = db->pagbuf;
308 char *new = twin;
309 register int smax = SPLTMAX;
310 apr_status_t status;
311
312 do {
313 /*
314 * split the current page
315 */
316 (void) splpage(pag, new, db->hmask + 1);
317 /*
318 * address of the new page
319 */
320 newp = (hash & db->hmask) | (db->hmask + 1);
321
322 /*
323 * write delay, read avoidence/cache shuffle:
324 * select the page for incoming pair: if key is to go to the new page,
325 * write out the previous one, and copy the new one over, thus making
326 * it the current page. If not, simply write the new page, and we are
327 * still looking at the page of interest. current page is not updated
328 * here, as sdbm_store will do so, after it inserts the incoming pair.
329 */
330 if (hash & (db->hmask + 1)) {
331 if ((status = write_page(db, db->pagbuf, db->pagbno))
332 != APR_SUCCESS)
333 return status;
334
335 db->pagbno = newp;
336 (void) memcpy(pag, new, PBLKSIZ);
337 }
338 else {
339 if ((status = write_page(db, new, newp)) != APR_SUCCESS)
340 return status;
341 }
342
343 if ((status = setdbit(db, db->curbit)) != APR_SUCCESS)
344 return status;
345 /*
346 * see if we have enough room now
347 */
348 if (fitpair(pag, need))
349 return APR_SUCCESS;
350 /*
351 * try again... update curbit and hmask as getpage would have
352 * done. because of our update of the current page, we do not
353 * need to read in anything. BUT we have to write the current
354 * [deferred] page out, as the window of failure is too great.
355 */
356 db->curbit = 2 * db->curbit
357 + ((hash & (db->hmask + 1)) ? 2 : 1);
358 db->hmask |= db->hmask + 1;
359
360 if ((status = write_page(db, db->pagbuf, db->pagbno))
361 != APR_SUCCESS)
362 return status;
363
364 } while (--smax);
365
366 /*
367 * if we are here, this is real bad news. After SPLTMAX splits,
368 * we still cannot fit the key. say goodnight.
369 */
370 #if 0
371 (void) write(2, "sdbm: cannot insert after SPLTMAX attempts.\n", 44);
372 #endif
373 /* ### ENOSPC not really appropriate but better than nothing */
374 return APR_ENOSPC;
375
376 }
377
378 /* Reads 'len' bytes from file 'f' at offset 'off' into buf.
379 * 'off' is given relative to the start of the file.
380 * If 'create' is asked and EOF is returned while reading, this is taken
381 * as success (i.e. a cleared buffer is returned).
382 */
read_from(apr_file_t * f,void * buf,apr_off_t off,apr_size_t len,int create)383 static apr_status_t read_from(apr_file_t *f, void *buf,
384 apr_off_t off, apr_size_t len,
385 int create)
386 {
387 apr_status_t status;
388
389 if ((status = apr_file_seek(f, APR_SET, &off)) != APR_SUCCESS ||
390 ((status = apr_file_read_full(f, buf, len, NULL)) != APR_SUCCESS)) {
391 /* if EOF is reached, pretend we read all zero's */
392 if (status == APR_EOF && create) {
393 memset(buf, 0, len);
394 status = APR_SUCCESS;
395 }
396 }
397
398 return status;
399 }
400
401 /*
402 * the following two routines will break if
403 * deletions aren't taken into account. (ndbm bug)
404 */
apr_sdbm_firstkey(apr_sdbm_t * db,apr_sdbm_datum_t * key)405 APU_DECLARE(apr_status_t) apr_sdbm_firstkey(apr_sdbm_t *db,
406 apr_sdbm_datum_t *key)
407 {
408 apr_status_t status;
409
410 if ((status = apr_sdbm_lock(db, APR_FLOCK_SHARED)) != APR_SUCCESS)
411 return status;
412
413 /*
414 * start at page 0
415 */
416 if ((status = getpage(db, 0, 1, 1)) == APR_SUCCESS) {
417 db->blkptr = 0;
418 db->keyptr = 0;
419 status = getnext(key, db);
420 }
421
422 (void) apr_sdbm_unlock(db);
423
424 return status;
425 }
426
apr_sdbm_nextkey(apr_sdbm_t * db,apr_sdbm_datum_t * key)427 APU_DECLARE(apr_status_t) apr_sdbm_nextkey(apr_sdbm_t *db,
428 apr_sdbm_datum_t *key)
429 {
430 apr_status_t status;
431
432 if ((status = apr_sdbm_lock(db, APR_FLOCK_SHARED)) != APR_SUCCESS)
433 return status;
434
435 status = getnext(key, db);
436
437 (void) apr_sdbm_unlock(db);
438
439 return status;
440 }
441
442 /*
443 * all important binary tree traversal
444 */
getpage(apr_sdbm_t * db,long hash,int by_num,int create)445 static apr_status_t getpage(apr_sdbm_t *db, long hash, int by_num, int create)
446 {
447 apr_status_t status;
448 register long pagb;
449
450 if (by_num) {
451 pagb = hash;
452 }
453 else {
454 register int hbit = 0;
455 register long dbit = 0;
456
457 while (dbit < db->maxbno && getdbit(db, dbit))
458 dbit = 2 * dbit + ((hash & (1 << hbit++)) ? 2 : 1);
459 debug(("dbit: %d...", dbit));
460
461 db->curbit = dbit;
462 db->hmask = masks[hbit];
463
464 pagb = hash & db->hmask;
465 }
466
467 /*
468 * see if the block we need is already in memory.
469 * note: this lookaside cache has about 10% hit rate.
470 */
471 if (pagb != db->pagbno) {
472 /*
473 * note: here, we assume a "hole" is read as 0s.
474 * if not, must zero pagbuf first.
475 * ### joe: this assumption was surely never correct? but
476 * ### we make it so in read_from anyway.
477 */
478 if ((status = read_from(db->pagf, db->pagbuf,
479 OFF_PAG(pagb), PBLKSIZ,
480 create)) != APR_SUCCESS)
481 return status;
482
483 if (!chkpage(db->pagbuf))
484 return APR_ENOSPC; /* ### better error? */
485
486 db->pagbno = pagb;
487
488 debug(("pag read: %d\n", pagb));
489 }
490 return APR_SUCCESS;
491 }
492
getdbit(apr_sdbm_t * db,long dbit)493 static int getdbit(apr_sdbm_t *db, long dbit)
494 {
495 register long c;
496 register long dirb;
497
498 c = dbit / BYTESIZ;
499 dirb = c / DBLKSIZ;
500
501 if (dirb != db->dirbno) {
502 if (read_from(db->dirf, db->dirbuf,
503 OFF_DIR(dirb), DBLKSIZ,
504 1) != APR_SUCCESS)
505 return 0;
506
507 db->dirbno = dirb;
508
509 debug(("dir read: %d\n", dirb));
510 }
511
512 return db->dirbuf[c % DBLKSIZ] & (1 << dbit % BYTESIZ);
513 }
514
setdbit(apr_sdbm_t * db,long dbit)515 static apr_status_t setdbit(apr_sdbm_t *db, long dbit)
516 {
517 register long c;
518 register long dirb;
519 apr_status_t status;
520 apr_off_t off;
521
522 c = dbit / BYTESIZ;
523 dirb = c / DBLKSIZ;
524
525 if (dirb != db->dirbno) {
526 if ((status = read_from(db->dirf, db->dirbuf,
527 OFF_DIR(dirb), DBLKSIZ,
528 1)) != APR_SUCCESS)
529 return status;
530
531 db->dirbno = dirb;
532
533 debug(("dir read: %d\n", dirb));
534 }
535
536 db->dirbuf[c % DBLKSIZ] |= (1 << dbit % BYTESIZ);
537
538 if (dbit >= db->maxbno)
539 db->maxbno += DBLKSIZ * BYTESIZ;
540
541 off = OFF_DIR(dirb);
542 if ((status = apr_file_seek(db->dirf, APR_SET, &off)) == APR_SUCCESS)
543 status = apr_file_write_full(db->dirf, db->dirbuf, DBLKSIZ, NULL);
544
545 return status;
546 }
547
548 /*
549 * getnext - get the next key in the page, and if done with
550 * the page, try the next page in sequence
551 */
getnext(apr_sdbm_datum_t * key,apr_sdbm_t * db)552 static apr_status_t getnext(apr_sdbm_datum_t *key, apr_sdbm_t *db)
553 {
554 apr_status_t status;
555 for (;;) {
556 db->keyptr++;
557 *key = getnkey(db->pagbuf, db->keyptr);
558 if (key->dptr != NULL)
559 return APR_SUCCESS;
560 /*
561 * we either run out, or there is nothing on this page..
562 * try the next one... If we lost our position on the
563 * file, we will have to seek.
564 */
565 db->blkptr++;
566 db->keyptr = 0;
567
568 /* ### EOF acceptable here too? */
569 if ((status = getpage(db, db->blkptr, 1, 0)) != APR_SUCCESS)
570 return status;
571 }
572
573 /* NOTREACHED */
574 }
575
576
apr_sdbm_rdonly(apr_sdbm_t * db)577 APU_DECLARE(int) apr_sdbm_rdonly(apr_sdbm_t *db)
578 {
579 /* ### Should we return true if the first lock is a share lock,
580 * to reflect that apr_sdbm_store and apr_sdbm_delete will fail?
581 */
582 return (db->flags & SDBM_RDONLY) != 0;
583 }
584
585