Commit | Line | Data |
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1 | /* |
2 | * sdbm - ndbm work-alike hashed database library |
3 | * based on Per-Aake Larson's Dynamic Hashing algorithms. BIT 18 (1978). |
4 | * author: oz@nexus.yorku.ca |
5 | * status: public domain. |
6 | * |
7 | * core routines |
8 | */ |
9 | |
10 | #ifndef lint |
11 | static char rcsid[] = "$Id: sdbm.c,v 1.16 90/12/13 13:01:31 oz Exp $"; |
12 | #endif |
13 | |
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14 | #include "config.h" |
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15 | #include "sdbm.h" |
16 | #include "tune.h" |
17 | #include "pair.h" |
18 | |
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19 | #ifdef I_FCNTL |
20 | # include <fcntl.h> |
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21 | #endif |
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22 | #ifdef I_SYS_FILE |
23 | # include <sys/file.h> |
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24 | #endif |
25 | |
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26 | #ifdef I_STRING |
27 | # include <string.h> |
28 | #else |
29 | # include <strings.h> |
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30 | #endif |
31 | |
32 | /* |
33 | * externals |
34 | */ |
35 | #ifndef sun |
36 | extern int errno; |
37 | #endif |
38 | |
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39 | extern Malloc_t malloc proto((MEM_SIZE)); |
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40 | extern Free_t free proto((Malloc_t)); |
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41 | extern Off_t lseek(); |
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42 | |
43 | /* |
44 | * forward |
45 | */ |
46 | static int getdbit proto((DBM *, long)); |
47 | static int setdbit proto((DBM *, long)); |
48 | static int getpage proto((DBM *, long)); |
49 | static datum getnext proto((DBM *)); |
50 | static int makroom proto((DBM *, long, int)); |
51 | |
52 | /* |
53 | * useful macros |
54 | */ |
55 | #define bad(x) ((x).dptr == NULL || (x).dsize < 0) |
56 | #define exhash(item) sdbm_hash((item).dptr, (item).dsize) |
57 | #define ioerr(db) ((db)->flags |= DBM_IOERR) |
58 | |
59 | #define OFF_PAG(off) (long) (off) * PBLKSIZ |
60 | #define OFF_DIR(off) (long) (off) * DBLKSIZ |
61 | |
62 | static long masks[] = { |
63 | 000000000000, 000000000001, 000000000003, 000000000007, |
64 | 000000000017, 000000000037, 000000000077, 000000000177, |
65 | 000000000377, 000000000777, 000000001777, 000000003777, |
66 | 000000007777, 000000017777, 000000037777, 000000077777, |
67 | 000000177777, 000000377777, 000000777777, 000001777777, |
68 | 000003777777, 000007777777, 000017777777, 000037777777, |
69 | 000077777777, 000177777777, 000377777777, 000777777777, |
70 | 001777777777, 003777777777, 007777777777, 017777777777 |
71 | }; |
72 | |
73 | datum nullitem = {NULL, 0}; |
74 | |
75 | DBM * |
76 | sdbm_open(file, flags, mode) |
77 | register char *file; |
78 | register int flags; |
79 | register int mode; |
80 | { |
81 | register DBM *db; |
82 | register char *dirname; |
83 | register char *pagname; |
84 | register int n; |
85 | |
86 | if (file == NULL || !*file) |
87 | return errno = EINVAL, (DBM *) NULL; |
88 | /* |
89 | * need space for two seperate filenames |
90 | */ |
91 | n = strlen(file) * 2 + strlen(DIRFEXT) + strlen(PAGFEXT) + 2; |
92 | |
93 | if ((dirname = malloc((unsigned) n)) == NULL) |
94 | return errno = ENOMEM, (DBM *) NULL; |
95 | /* |
96 | * build the file names |
97 | */ |
98 | dirname = strcat(strcpy(dirname, file), DIRFEXT); |
99 | pagname = strcpy(dirname + strlen(dirname) + 1, file); |
100 | pagname = strcat(pagname, PAGFEXT); |
101 | |
102 | db = sdbm_prep(dirname, pagname, flags, mode); |
103 | free((char *) dirname); |
104 | return db; |
105 | } |
106 | |
107 | DBM * |
108 | sdbm_prep(dirname, pagname, flags, mode) |
109 | char *dirname; |
110 | char *pagname; |
111 | int flags; |
112 | int mode; |
113 | { |
114 | register DBM *db; |
115 | struct stat dstat; |
116 | |
117 | if ((db = (DBM *) malloc(sizeof(DBM))) == NULL) |
118 | return errno = ENOMEM, (DBM *) NULL; |
119 | |
120 | db->flags = 0; |
121 | db->hmask = 0; |
122 | db->blkptr = 0; |
123 | db->keyptr = 0; |
124 | /* |
125 | * adjust user flags so that WRONLY becomes RDWR, |
126 | * as required by this package. Also set our internal |
127 | * flag for RDONLY if needed. |
128 | */ |
129 | if (flags & O_WRONLY) |
130 | flags = (flags & ~O_WRONLY) | O_RDWR; |
131 | |
132 | else if ((flags & 03) == O_RDONLY) |
133 | db->flags = DBM_RDONLY; |
134 | /* |
135 | * open the files in sequence, and stat the dirfile. |
136 | * If we fail anywhere, undo everything, return NULL. |
137 | */ |
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138 | # ifdef OS2 |
139 | flags |= O_BINARY; |
140 | # endif |
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141 | if ((db->pagf = open(pagname, flags, mode)) > -1) { |
142 | if ((db->dirf = open(dirname, flags, mode)) > -1) { |
143 | /* |
144 | * need the dirfile size to establish max bit number. |
145 | */ |
146 | if (fstat(db->dirf, &dstat) == 0) { |
147 | /* |
148 | * zero size: either a fresh database, or one with a single, |
149 | * unsplit data page: dirpage is all zeros. |
150 | */ |
151 | db->dirbno = (!dstat.st_size) ? 0 : -1; |
152 | db->pagbno = -1; |
153 | db->maxbno = dstat.st_size * BYTESIZ; |
154 | |
155 | (void) memset(db->pagbuf, 0, PBLKSIZ); |
156 | (void) memset(db->dirbuf, 0, DBLKSIZ); |
157 | /* |
158 | * success |
159 | */ |
160 | return db; |
161 | } |
162 | (void) close(db->dirf); |
163 | } |
164 | (void) close(db->pagf); |
165 | } |
166 | free((char *) db); |
167 | return (DBM *) NULL; |
168 | } |
169 | |
170 | void |
171 | sdbm_close(db) |
172 | register DBM *db; |
173 | { |
174 | if (db == NULL) |
175 | errno = EINVAL; |
176 | else { |
177 | (void) close(db->dirf); |
178 | (void) close(db->pagf); |
179 | free((char *) db); |
180 | } |
181 | } |
182 | |
183 | datum |
184 | sdbm_fetch(db, key) |
185 | register DBM *db; |
186 | datum key; |
187 | { |
188 | if (db == NULL || bad(key)) |
189 | return errno = EINVAL, nullitem; |
190 | |
191 | if (getpage(db, exhash(key))) |
192 | return getpair(db->pagbuf, key); |
193 | |
194 | return ioerr(db), nullitem; |
195 | } |
196 | |
197 | int |
198 | sdbm_delete(db, key) |
199 | register DBM *db; |
200 | datum key; |
201 | { |
202 | if (db == NULL || bad(key)) |
203 | return errno = EINVAL, -1; |
204 | if (sdbm_rdonly(db)) |
205 | return errno = EPERM, -1; |
206 | |
207 | if (getpage(db, exhash(key))) { |
208 | if (!delpair(db->pagbuf, key)) |
209 | return -1; |
210 | /* |
211 | * update the page file |
212 | */ |
213 | if (lseek(db->pagf, OFF_PAG(db->pagbno), SEEK_SET) < 0 |
214 | || write(db->pagf, db->pagbuf, PBLKSIZ) < 0) |
215 | return ioerr(db), -1; |
216 | |
217 | return 0; |
218 | } |
219 | |
220 | return ioerr(db), -1; |
221 | } |
222 | |
223 | int |
224 | sdbm_store(db, key, val, flags) |
225 | register DBM *db; |
226 | datum key; |
227 | datum val; |
228 | int flags; |
229 | { |
230 | int need; |
231 | register long hash; |
232 | |
233 | if (db == NULL || bad(key)) |
234 | return errno = EINVAL, -1; |
235 | if (sdbm_rdonly(db)) |
236 | return errno = EPERM, -1; |
237 | |
238 | need = key.dsize + val.dsize; |
239 | /* |
240 | * is the pair too big (or too small) for this database ?? |
241 | */ |
242 | if (need < 0 || need > PAIRMAX) |
243 | return errno = EINVAL, -1; |
244 | |
245 | if (getpage(db, (hash = exhash(key)))) { |
246 | /* |
247 | * if we need to replace, delete the key/data pair |
248 | * first. If it is not there, ignore. |
249 | */ |
250 | if (flags == DBM_REPLACE) |
251 | (void) delpair(db->pagbuf, key); |
252 | #ifdef SEEDUPS |
253 | else if (duppair(db->pagbuf, key)) |
254 | return 1; |
255 | #endif |
256 | /* |
257 | * if we do not have enough room, we have to split. |
258 | */ |
259 | if (!fitpair(db->pagbuf, need)) |
260 | if (!makroom(db, hash, need)) |
261 | return ioerr(db), -1; |
262 | /* |
263 | * we have enough room or split is successful. insert the key, |
264 | * and update the page file. |
265 | */ |
266 | (void) putpair(db->pagbuf, key, val); |
267 | |
268 | if (lseek(db->pagf, OFF_PAG(db->pagbno), SEEK_SET) < 0 |
269 | || write(db->pagf, db->pagbuf, PBLKSIZ) < 0) |
270 | return ioerr(db), -1; |
271 | /* |
272 | * success |
273 | */ |
274 | return 0; |
275 | } |
276 | |
277 | return ioerr(db), -1; |
278 | } |
279 | |
280 | /* |
281 | * makroom - make room by splitting the overfull page |
282 | * this routine will attempt to make room for SPLTMAX times before |
283 | * giving up. |
284 | */ |
285 | static int |
286 | makroom(db, hash, need) |
287 | register DBM *db; |
288 | long hash; |
289 | int need; |
290 | { |
291 | long newp; |
292 | char twin[PBLKSIZ]; |
293 | char *pag = db->pagbuf; |
294 | char *new = twin; |
295 | register int smax = SPLTMAX; |
296 | |
297 | do { |
298 | /* |
299 | * split the current page |
300 | */ |
301 | (void) splpage(pag, new, db->hmask + 1); |
302 | /* |
303 | * address of the new page |
304 | */ |
305 | newp = (hash & db->hmask) | (db->hmask + 1); |
306 | |
307 | /* |
308 | * write delay, read avoidence/cache shuffle: |
309 | * select the page for incoming pair: if key is to go to the new page, |
310 | * write out the previous one, and copy the new one over, thus making |
311 | * it the current page. If not, simply write the new page, and we are |
312 | * still looking at the page of interest. current page is not updated |
313 | * here, as sdbm_store will do so, after it inserts the incoming pair. |
314 | */ |
315 | if (hash & (db->hmask + 1)) { |
316 | if (lseek(db->pagf, OFF_PAG(db->pagbno), SEEK_SET) < 0 |
317 | || write(db->pagf, db->pagbuf, PBLKSIZ) < 0) |
318 | return 0; |
319 | db->pagbno = newp; |
320 | (void) memcpy(pag, new, PBLKSIZ); |
321 | } |
322 | else if (lseek(db->pagf, OFF_PAG(newp), SEEK_SET) < 0 |
323 | || write(db->pagf, new, PBLKSIZ) < 0) |
324 | return 0; |
325 | |
326 | if (!setdbit(db, db->curbit)) |
327 | return 0; |
328 | /* |
329 | * see if we have enough room now |
330 | */ |
331 | if (fitpair(pag, need)) |
332 | return 1; |
333 | /* |
334 | * try again... update curbit and hmask as getpage would have |
335 | * done. because of our update of the current page, we do not |
336 | * need to read in anything. BUT we have to write the current |
337 | * [deferred] page out, as the window of failure is too great. |
338 | */ |
339 | db->curbit = 2 * db->curbit + |
340 | ((hash & (db->hmask + 1)) ? 2 : 1); |
341 | db->hmask |= db->hmask + 1; |
342 | |
343 | if (lseek(db->pagf, OFF_PAG(db->pagbno), SEEK_SET) < 0 |
344 | || write(db->pagf, db->pagbuf, PBLKSIZ) < 0) |
345 | return 0; |
346 | |
347 | } while (--smax); |
348 | /* |
349 | * if we are here, this is real bad news. After SPLTMAX splits, |
350 | * we still cannot fit the key. say goodnight. |
351 | */ |
352 | #ifdef BADMESS |
353 | (void) write(2, "sdbm: cannot insert after SPLTMAX attempts.\n", 44); |
354 | #endif |
355 | return 0; |
356 | |
357 | } |
358 | |
359 | /* |
360 | * the following two routines will break if |
361 | * deletions aren't taken into account. (ndbm bug) |
362 | */ |
363 | datum |
364 | sdbm_firstkey(db) |
365 | register DBM *db; |
366 | { |
367 | if (db == NULL) |
368 | return errno = EINVAL, nullitem; |
369 | /* |
370 | * start at page 0 |
371 | */ |
372 | if (lseek(db->pagf, OFF_PAG(0), SEEK_SET) < 0 |
373 | || read(db->pagf, db->pagbuf, PBLKSIZ) < 0) |
374 | return ioerr(db), nullitem; |
375 | db->pagbno = 0; |
376 | db->blkptr = 0; |
377 | db->keyptr = 0; |
378 | |
379 | return getnext(db); |
380 | } |
381 | |
382 | datum |
383 | sdbm_nextkey(db) |
384 | register DBM *db; |
385 | { |
386 | if (db == NULL) |
387 | return errno = EINVAL, nullitem; |
388 | return getnext(db); |
389 | } |
390 | |
391 | /* |
392 | * all important binary trie traversal |
393 | */ |
394 | static int |
395 | getpage(db, hash) |
396 | register DBM *db; |
397 | register long hash; |
398 | { |
399 | register int hbit; |
400 | register long dbit; |
401 | register long pagb; |
402 | |
403 | dbit = 0; |
404 | hbit = 0; |
405 | while (dbit < db->maxbno && getdbit(db, dbit)) |
406 | dbit = 2 * dbit + ((hash & (1 << hbit++)) ? 2 : 1); |
407 | |
408 | debug(("dbit: %d...", dbit)); |
409 | |
410 | db->curbit = dbit; |
411 | db->hmask = masks[hbit]; |
412 | |
413 | pagb = hash & db->hmask; |
414 | /* |
415 | * see if the block we need is already in memory. |
416 | * note: this lookaside cache has about 10% hit rate. |
417 | */ |
418 | if (pagb != db->pagbno) { |
419 | /* |
420 | * note: here, we assume a "hole" is read as 0s. |
421 | * if not, must zero pagbuf first. |
422 | */ |
423 | if (lseek(db->pagf, OFF_PAG(pagb), SEEK_SET) < 0 |
424 | || read(db->pagf, db->pagbuf, PBLKSIZ) < 0) |
425 | return 0; |
426 | if (!chkpage(db->pagbuf)) |
427 | return 0; |
428 | db->pagbno = pagb; |
429 | |
430 | debug(("pag read: %d\n", pagb)); |
431 | } |
432 | return 1; |
433 | } |
434 | |
435 | static int |
436 | getdbit(db, dbit) |
437 | register DBM *db; |
438 | register long dbit; |
439 | { |
440 | register long c; |
441 | register long dirb; |
442 | |
443 | c = dbit / BYTESIZ; |
444 | dirb = c / DBLKSIZ; |
445 | |
446 | if (dirb != db->dirbno) { |
447 | if (lseek(db->dirf, OFF_DIR(dirb), SEEK_SET) < 0 |
448 | || read(db->dirf, db->dirbuf, DBLKSIZ) < 0) |
449 | return 0; |
450 | db->dirbno = dirb; |
451 | |
452 | debug(("dir read: %d\n", dirb)); |
453 | } |
454 | |
455 | return db->dirbuf[c % DBLKSIZ] & (1 << dbit % BYTESIZ); |
456 | } |
457 | |
458 | static int |
459 | setdbit(db, dbit) |
460 | register DBM *db; |
461 | register long dbit; |
462 | { |
463 | register long c; |
464 | register long dirb; |
465 | |
466 | c = dbit / BYTESIZ; |
467 | dirb = c / DBLKSIZ; |
468 | |
469 | if (dirb != db->dirbno) { |
470 | if (lseek(db->dirf, OFF_DIR(dirb), SEEK_SET) < 0 |
471 | || read(db->dirf, db->dirbuf, DBLKSIZ) < 0) |
472 | return 0; |
473 | db->dirbno = dirb; |
474 | |
475 | debug(("dir read: %d\n", dirb)); |
476 | } |
477 | |
478 | db->dirbuf[c % DBLKSIZ] |= (1 << dbit % BYTESIZ); |
479 | |
480 | if (dbit >= db->maxbno) |
481 | db->maxbno += DBLKSIZ * BYTESIZ; |
482 | |
483 | if (lseek(db->dirf, OFF_DIR(dirb), SEEK_SET) < 0 |
484 | || write(db->dirf, db->dirbuf, DBLKSIZ) < 0) |
485 | return 0; |
486 | |
487 | return 1; |
488 | } |
489 | |
490 | /* |
491 | * getnext - get the next key in the page, and if done with |
492 | * the page, try the next page in sequence |
493 | */ |
494 | static datum |
495 | getnext(db) |
496 | register DBM *db; |
497 | { |
498 | datum key; |
499 | |
500 | for (;;) { |
501 | db->keyptr++; |
502 | key = getnkey(db->pagbuf, db->keyptr); |
503 | if (key.dptr != NULL) |
504 | return key; |
505 | /* |
506 | * we either run out, or there is nothing on this page.. |
507 | * try the next one... If we lost our position on the |
508 | * file, we will have to seek. |
509 | */ |
510 | db->keyptr = 0; |
511 | if (db->pagbno != db->blkptr++) |
512 | if (lseek(db->pagf, OFF_PAG(db->blkptr), SEEK_SET) < 0) |
513 | break; |
514 | db->pagbno = db->blkptr; |
515 | if (read(db->pagf, db->pagbuf, PBLKSIZ) <= 0) |
516 | break; |
517 | if (!chkpage(db->pagbuf)) |
518 | break; |
519 | } |
520 | |
521 | return ioerr(db), nullitem; |
522 | } |
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523 | |