Commit | Line | Data |
463ee0b2 |
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 | |
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10 | #include "INTERN.h" |
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11 | #include "config.h" |
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12 | #ifdef WIN32 |
13 | #include "io.h" |
14 | #endif |
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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 | */ |
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35 | #ifndef WIN32 |
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36 | #ifndef sun |
37 | extern int errno; |
38 | #endif |
39 | |
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40 | extern Malloc_t malloc proto((MEM_SIZE)); |
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41 | extern Free_t free proto((Malloc_t)); |
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42 | extern Off_t lseek(int, Off_t, int); |
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43 | #endif |
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44 | |
45 | /* |
46 | * forward |
47 | */ |
48 | static int getdbit proto((DBM *, long)); |
49 | static int setdbit proto((DBM *, long)); |
50 | static int getpage proto((DBM *, long)); |
51 | static datum getnext proto((DBM *)); |
52 | static int makroom proto((DBM *, long, int)); |
53 | |
54 | /* |
55 | * useful macros |
56 | */ |
57 | #define bad(x) ((x).dptr == NULL || (x).dsize < 0) |
58 | #define exhash(item) sdbm_hash((item).dptr, (item).dsize) |
59 | #define ioerr(db) ((db)->flags |= DBM_IOERR) |
60 | |
61 | #define OFF_PAG(off) (long) (off) * PBLKSIZ |
62 | #define OFF_DIR(off) (long) (off) * DBLKSIZ |
63 | |
64 | static long masks[] = { |
65 | 000000000000, 000000000001, 000000000003, 000000000007, |
66 | 000000000017, 000000000037, 000000000077, 000000000177, |
67 | 000000000377, 000000000777, 000000001777, 000000003777, |
68 | 000000007777, 000000017777, 000000037777, 000000077777, |
69 | 000000177777, 000000377777, 000000777777, 000001777777, |
70 | 000003777777, 000007777777, 000017777777, 000037777777, |
71 | 000077777777, 000177777777, 000377777777, 000777777777, |
72 | 001777777777, 003777777777, 007777777777, 017777777777 |
73 | }; |
74 | |
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75 | DBM * |
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76 | sdbm_open(register char *file, register int flags, register int mode) |
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77 | { |
78 | register DBM *db; |
79 | register char *dirname; |
80 | register char *pagname; |
81 | register int n; |
82 | |
83 | if (file == NULL || !*file) |
84 | return errno = EINVAL, (DBM *) NULL; |
85 | /* |
86 | * need space for two seperate filenames |
87 | */ |
88 | n = strlen(file) * 2 + strlen(DIRFEXT) + strlen(PAGFEXT) + 2; |
89 | |
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90 | if ((dirname = (char *) malloc((unsigned) n)) == NULL) |
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91 | return errno = ENOMEM, (DBM *) NULL; |
92 | /* |
93 | * build the file names |
94 | */ |
95 | dirname = strcat(strcpy(dirname, file), DIRFEXT); |
96 | pagname = strcpy(dirname + strlen(dirname) + 1, file); |
97 | pagname = strcat(pagname, PAGFEXT); |
98 | |
99 | db = sdbm_prep(dirname, pagname, flags, mode); |
100 | free((char *) dirname); |
101 | return db; |
102 | } |
103 | |
104 | DBM * |
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105 | sdbm_prep(char *dirname, char *pagname, int flags, int mode) |
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106 | { |
107 | register DBM *db; |
108 | struct stat dstat; |
109 | |
110 | if ((db = (DBM *) malloc(sizeof(DBM))) == NULL) |
111 | return errno = ENOMEM, (DBM *) NULL; |
112 | |
113 | db->flags = 0; |
114 | db->hmask = 0; |
115 | db->blkptr = 0; |
116 | db->keyptr = 0; |
117 | /* |
118 | * adjust user flags so that WRONLY becomes RDWR, |
119 | * as required by this package. Also set our internal |
120 | * flag for RDONLY if needed. |
121 | */ |
122 | if (flags & O_WRONLY) |
123 | flags = (flags & ~O_WRONLY) | O_RDWR; |
124 | |
125 | else if ((flags & 03) == O_RDONLY) |
126 | db->flags = DBM_RDONLY; |
127 | /* |
128 | * open the files in sequence, and stat the dirfile. |
129 | * If we fail anywhere, undo everything, return NULL. |
130 | */ |
d493b042 |
131 | #if defined(OS2) || defined(MSDOS) || defined(WIN32) || defined(CYGWIN) |
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132 | flags |= O_BINARY; |
133 | # endif |
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134 | if ((db->pagf = open(pagname, flags, mode)) > -1) { |
135 | if ((db->dirf = open(dirname, flags, mode)) > -1) { |
136 | /* |
137 | * need the dirfile size to establish max bit number. |
138 | */ |
139 | if (fstat(db->dirf, &dstat) == 0) { |
140 | /* |
141 | * zero size: either a fresh database, or one with a single, |
142 | * unsplit data page: dirpage is all zeros. |
143 | */ |
144 | db->dirbno = (!dstat.st_size) ? 0 : -1; |
145 | db->pagbno = -1; |
146 | db->maxbno = dstat.st_size * BYTESIZ; |
147 | |
148 | (void) memset(db->pagbuf, 0, PBLKSIZ); |
149 | (void) memset(db->dirbuf, 0, DBLKSIZ); |
150 | /* |
151 | * success |
152 | */ |
153 | return db; |
154 | } |
155 | (void) close(db->dirf); |
156 | } |
157 | (void) close(db->pagf); |
158 | } |
159 | free((char *) db); |
160 | return (DBM *) NULL; |
161 | } |
162 | |
163 | void |
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164 | sdbm_close(register DBM *db) |
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165 | { |
166 | if (db == NULL) |
167 | errno = EINVAL; |
168 | else { |
169 | (void) close(db->dirf); |
170 | (void) close(db->pagf); |
171 | free((char *) db); |
172 | } |
173 | } |
174 | |
175 | datum |
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176 | sdbm_fetch(register DBM *db, datum key) |
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177 | { |
178 | if (db == NULL || bad(key)) |
179 | return errno = EINVAL, nullitem; |
180 | |
181 | if (getpage(db, exhash(key))) |
182 | return getpair(db->pagbuf, key); |
183 | |
184 | return ioerr(db), nullitem; |
185 | } |
186 | |
187 | int |
f4b9d880 |
188 | sdbm_exists(register DBM *db, datum key) |
189 | { |
190 | if (db == NULL || bad(key)) |
191 | return errno = EINVAL, -1; |
192 | |
193 | if (getpage(db, exhash(key))) |
194 | return exipair(db->pagbuf, key); |
195 | |
196 | return ioerr(db), -1; |
197 | } |
198 | |
199 | int |
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200 | sdbm_delete(register DBM *db, datum key) |
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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 |
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224 | sdbm_store(register DBM *db, datum key, datum val, int flags) |
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225 | { |
226 | int need; |
227 | register long hash; |
228 | |
229 | if (db == NULL || bad(key)) |
230 | return errno = EINVAL, -1; |
231 | if (sdbm_rdonly(db)) |
232 | return errno = EPERM, -1; |
233 | |
234 | need = key.dsize + val.dsize; |
235 | /* |
236 | * is the pair too big (or too small) for this database ?? |
237 | */ |
238 | if (need < 0 || need > PAIRMAX) |
239 | return errno = EINVAL, -1; |
240 | |
241 | if (getpage(db, (hash = exhash(key)))) { |
242 | /* |
243 | * if we need to replace, delete the key/data pair |
244 | * first. If it is not there, ignore. |
245 | */ |
246 | if (flags == DBM_REPLACE) |
247 | (void) delpair(db->pagbuf, key); |
248 | #ifdef SEEDUPS |
249 | else if (duppair(db->pagbuf, key)) |
250 | return 1; |
251 | #endif |
252 | /* |
253 | * if we do not have enough room, we have to split. |
254 | */ |
255 | if (!fitpair(db->pagbuf, need)) |
256 | if (!makroom(db, hash, need)) |
257 | return ioerr(db), -1; |
258 | /* |
259 | * we have enough room or split is successful. insert the key, |
260 | * and update the page file. |
261 | */ |
262 | (void) putpair(db->pagbuf, key, val); |
263 | |
264 | if (lseek(db->pagf, OFF_PAG(db->pagbno), SEEK_SET) < 0 |
265 | || write(db->pagf, db->pagbuf, PBLKSIZ) < 0) |
266 | return ioerr(db), -1; |
267 | /* |
268 | * success |
269 | */ |
270 | return 0; |
271 | } |
272 | |
273 | return ioerr(db), -1; |
274 | } |
275 | |
276 | /* |
277 | * makroom - make room by splitting the overfull page |
278 | * this routine will attempt to make room for SPLTMAX times before |
279 | * giving up. |
280 | */ |
281 | static int |
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282 | makroom(register DBM *db, long int hash, int need) |
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283 | { |
284 | long newp; |
285 | char twin[PBLKSIZ]; |
286 | char *pag = db->pagbuf; |
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287 | char *New = twin; |
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288 | register int smax = SPLTMAX; |
289 | |
290 | do { |
291 | /* |
292 | * split the current page |
293 | */ |
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294 | (void) splpage(pag, New, db->hmask + 1); |
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295 | /* |
296 | * address of the new page |
297 | */ |
298 | newp = (hash & db->hmask) | (db->hmask + 1); |
299 | |
300 | /* |
301 | * write delay, read avoidence/cache shuffle: |
302 | * select the page for incoming pair: if key is to go to the new page, |
303 | * write out the previous one, and copy the new one over, thus making |
304 | * it the current page. If not, simply write the new page, and we are |
305 | * still looking at the page of interest. current page is not updated |
306 | * here, as sdbm_store will do so, after it inserts the incoming pair. |
307 | */ |
308 | if (hash & (db->hmask + 1)) { |
309 | if (lseek(db->pagf, OFF_PAG(db->pagbno), SEEK_SET) < 0 |
310 | || write(db->pagf, db->pagbuf, PBLKSIZ) < 0) |
311 | return 0; |
312 | db->pagbno = newp; |
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313 | (void) memcpy(pag, New, PBLKSIZ); |
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314 | } |
315 | else if (lseek(db->pagf, OFF_PAG(newp), SEEK_SET) < 0 |
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316 | || write(db->pagf, New, PBLKSIZ) < 0) |
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317 | return 0; |
318 | |
319 | if (!setdbit(db, db->curbit)) |
320 | return 0; |
321 | /* |
322 | * see if we have enough room now |
323 | */ |
324 | if (fitpair(pag, need)) |
325 | return 1; |
326 | /* |
327 | * try again... update curbit and hmask as getpage would have |
328 | * done. because of our update of the current page, we do not |
329 | * need to read in anything. BUT we have to write the current |
330 | * [deferred] page out, as the window of failure is too great. |
331 | */ |
332 | db->curbit = 2 * db->curbit + |
333 | ((hash & (db->hmask + 1)) ? 2 : 1); |
334 | db->hmask |= db->hmask + 1; |
335 | |
336 | if (lseek(db->pagf, OFF_PAG(db->pagbno), SEEK_SET) < 0 |
337 | || write(db->pagf, db->pagbuf, PBLKSIZ) < 0) |
338 | return 0; |
339 | |
340 | } while (--smax); |
341 | /* |
342 | * if we are here, this is real bad news. After SPLTMAX splits, |
343 | * we still cannot fit the key. say goodnight. |
344 | */ |
345 | #ifdef BADMESS |
346 | (void) write(2, "sdbm: cannot insert after SPLTMAX attempts.\n", 44); |
347 | #endif |
348 | return 0; |
349 | |
350 | } |
351 | |
352 | /* |
353 | * the following two routines will break if |
354 | * deletions aren't taken into account. (ndbm bug) |
355 | */ |
356 | datum |
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357 | sdbm_firstkey(register DBM *db) |
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358 | { |
359 | if (db == NULL) |
360 | return errno = EINVAL, nullitem; |
361 | /* |
362 | * start at page 0 |
363 | */ |
364 | if (lseek(db->pagf, OFF_PAG(0), SEEK_SET) < 0 |
365 | || read(db->pagf, db->pagbuf, PBLKSIZ) < 0) |
366 | return ioerr(db), nullitem; |
367 | db->pagbno = 0; |
368 | db->blkptr = 0; |
369 | db->keyptr = 0; |
370 | |
371 | return getnext(db); |
372 | } |
373 | |
374 | datum |
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375 | sdbm_nextkey(register DBM *db) |
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376 | { |
377 | if (db == NULL) |
378 | return errno = EINVAL, nullitem; |
379 | return getnext(db); |
380 | } |
381 | |
382 | /* |
383 | * all important binary trie traversal |
384 | */ |
385 | static int |
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386 | getpage(register DBM *db, register long int hash) |
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387 | { |
388 | register int hbit; |
389 | register long dbit; |
390 | register long pagb; |
391 | |
392 | dbit = 0; |
393 | hbit = 0; |
394 | while (dbit < db->maxbno && getdbit(db, dbit)) |
395 | dbit = 2 * dbit + ((hash & (1 << hbit++)) ? 2 : 1); |
396 | |
397 | debug(("dbit: %d...", dbit)); |
398 | |
399 | db->curbit = dbit; |
400 | db->hmask = masks[hbit]; |
401 | |
402 | pagb = hash & db->hmask; |
403 | /* |
404 | * see if the block we need is already in memory. |
405 | * note: this lookaside cache has about 10% hit rate. |
406 | */ |
407 | if (pagb != db->pagbno) { |
408 | /* |
409 | * note: here, we assume a "hole" is read as 0s. |
410 | * if not, must zero pagbuf first. |
411 | */ |
412 | if (lseek(db->pagf, OFF_PAG(pagb), SEEK_SET) < 0 |
413 | || read(db->pagf, db->pagbuf, PBLKSIZ) < 0) |
414 | return 0; |
415 | if (!chkpage(db->pagbuf)) |
416 | return 0; |
417 | db->pagbno = pagb; |
418 | |
419 | debug(("pag read: %d\n", pagb)); |
420 | } |
421 | return 1; |
422 | } |
423 | |
424 | static int |
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425 | getdbit(register DBM *db, register long int dbit) |
463ee0b2 |
426 | { |
427 | register long c; |
428 | register long dirb; |
429 | |
430 | c = dbit / BYTESIZ; |
431 | dirb = c / DBLKSIZ; |
432 | |
433 | if (dirb != db->dirbno) { |
434 | if (lseek(db->dirf, OFF_DIR(dirb), SEEK_SET) < 0 |
435 | || read(db->dirf, db->dirbuf, DBLKSIZ) < 0) |
436 | return 0; |
437 | db->dirbno = dirb; |
438 | |
439 | debug(("dir read: %d\n", dirb)); |
440 | } |
441 | |
442 | return db->dirbuf[c % DBLKSIZ] & (1 << dbit % BYTESIZ); |
443 | } |
444 | |
445 | static int |
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446 | setdbit(register DBM *db, register long int dbit) |
463ee0b2 |
447 | { |
448 | register long c; |
449 | register long dirb; |
450 | |
451 | c = dbit / BYTESIZ; |
452 | dirb = c / DBLKSIZ; |
453 | |
454 | if (dirb != db->dirbno) { |
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455 | (void) memset(db->dirbuf, 0, DBLKSIZ); |
463ee0b2 |
456 | if (lseek(db->dirf, OFF_DIR(dirb), SEEK_SET) < 0 |
457 | || read(db->dirf, db->dirbuf, DBLKSIZ) < 0) |
458 | return 0; |
459 | db->dirbno = dirb; |
460 | |
461 | debug(("dir read: %d\n", dirb)); |
462 | } |
463 | |
464 | db->dirbuf[c % DBLKSIZ] |= (1 << dbit % BYTESIZ); |
465 | |
466 | if (dbit >= db->maxbno) |
467 | db->maxbno += DBLKSIZ * BYTESIZ; |
468 | |
469 | if (lseek(db->dirf, OFF_DIR(dirb), SEEK_SET) < 0 |
470 | || write(db->dirf, db->dirbuf, DBLKSIZ) < 0) |
471 | return 0; |
472 | |
473 | return 1; |
474 | } |
475 | |
476 | /* |
477 | * getnext - get the next key in the page, and if done with |
478 | * the page, try the next page in sequence |
479 | */ |
480 | static datum |
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481 | getnext(register DBM *db) |
463ee0b2 |
482 | { |
483 | datum key; |
484 | |
485 | for (;;) { |
486 | db->keyptr++; |
487 | key = getnkey(db->pagbuf, db->keyptr); |
488 | if (key.dptr != NULL) |
489 | return key; |
490 | /* |
491 | * we either run out, or there is nothing on this page.. |
492 | * try the next one... If we lost our position on the |
493 | * file, we will have to seek. |
494 | */ |
495 | db->keyptr = 0; |
496 | if (db->pagbno != db->blkptr++) |
497 | if (lseek(db->pagf, OFF_PAG(db->blkptr), SEEK_SET) < 0) |
498 | break; |
499 | db->pagbno = db->blkptr; |
500 | if (read(db->pagf, db->pagbuf, PBLKSIZ) <= 0) |
501 | break; |
502 | if (!chkpage(db->pagbuf)) |
503 | break; |
504 | } |
505 | |
506 | return ioerr(db), nullitem; |
507 | } |
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508 | |