1 /** $MirOS: src/lib/libc/db/hash/hash_page.c,v 1.3 2005/09/22 20:07:47 tg Exp $ */
2 /* $OpenBSD: hash_page.c,v 1.17 2005/08/05 13:03:00 espie Exp $ */
3
4 /*-
5 * Copyright (c) 1990, 1993, 1994
6 * The Regents of the University of California. All rights reserved.
7 *
8 * This code is derived from software contributed to Berkeley by
9 * Margo Seltzer.
10 *
11 * Redistribution and use in source and binary forms, with or without
12 * modification, are permitted provided that the following conditions
13 * are met:
14 * 1. Redistributions of source code must retain the above copyright
15 * notice, this list of conditions and the following disclaimer.
16 * 2. Redistributions in binary form must reproduce the above copyright
17 * notice, this list of conditions and the following disclaimer in the
18 * documentation and/or other materials provided with the distribution.
19 * 3. Neither the name of the University nor the names of its contributors
20 * may be used to endorse or promote products derived from this software
21 * without specific prior written permission.
22 *
23 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
24 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
25 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
26 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
27 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
28 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
29 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
30 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
31 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
32 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
33 * SUCH DAMAGE.
34 */
35
36 /*
37 * PACKAGE: hashing
38 *
39 * DESCRIPTION:
40 * Page manipulation for hashing package.
41 *
42 * ROUTINES:
43 *
44 * External
45 * __get_page
46 * __add_ovflpage
47 * Internal
48 * overflow_page
49 * open_temp
50 */
51
52 #include <sys/param.h>
53
54 #include <errno.h>
55 #include <fcntl.h>
56 #include <signal.h>
57 #include <stdio.h>
58 #include <stdlib.h>
59 #include <string.h>
60 #include <unistd.h>
61 #ifdef DEBUG
62 #include <assert.h>
63 #endif
64
65 #include <db.h>
66 #include "hash.h"
67 #include "page.h"
68 #include "extern.h"
69
70 __SCCSID("@(#)hash_page.c 8.7 (Berkeley) 8/16/94");
71 __RCSID("$MirOS: src/lib/libc/db/hash/hash_page.c,v 1.3 2005/09/22 20:07:47 tg Exp $");
72
73 static u_int32_t *fetch_bitmap(HTAB *, int);
74 static u_int32_t first_free(u_int32_t);
75 static int open_temp(HTAB *);
76 static u_int16_t overflow_page(HTAB *);
77 static void putpair(char *, const DBT *, const DBT *);
78 static void squeeze_key(u_int16_t *, const DBT *, const DBT *);
79 static int ugly_split(HTAB *, u_int32_t, BUFHEAD *, BUFHEAD *, int, int);
80
81 #define PAGE_INIT(P) { \
82 ((u_int16_t *)(P))[0] = 0; \
83 ((u_int16_t *)(P))[1] = hashp->BSIZE - 3 * sizeof(u_int16_t); \
84 ((u_int16_t *)(P))[2] = hashp->BSIZE; \
85 }
86
87 /*
88 * This is called AFTER we have verified that there is room on the page for
89 * the pair (PAIRFITS has returned true) so we go right ahead and start moving
90 * stuff on.
91 */
92 static void
putpair(char * p,const DBT * key,const DBT * val)93 putpair(char *p, const DBT *key, const DBT *val)
94 {
95 u_int16_t *bp, n, off;
96
97 bp = (u_int16_t *)p;
98
99 /* Enter the key first. */
100 n = bp[0];
101
102 off = OFFSET(bp) - key->size;
103 memmove(p + off, key->data, key->size);
104 bp[++n] = off;
105
106 /* Now the data. */
107 off -= val->size;
108 memmove(p + off, val->data, val->size);
109 bp[++n] = off;
110
111 /* Adjust page info. */
112 bp[0] = n;
113 bp[n + 1] = off - ((n + 3) * sizeof(u_int16_t));
114 bp[n + 2] = off;
115 }
116
117 /*
118 * Returns:
119 * 0 OK
120 * -1 error
121 */
122 int
__delpair(HTAB * hashp,BUFHEAD * bufp,int ndx)123 __delpair(HTAB *hashp, BUFHEAD *bufp, int ndx)
124 {
125 u_int16_t *bp, newoff, pairlen;
126 int n;
127
128 bp = (u_int16_t *)bufp->page;
129 n = bp[0];
130
131 if (bp[ndx + 1] < REAL_KEY)
132 return (__big_delete(hashp, bufp));
133 if (ndx != 1)
134 newoff = bp[ndx - 1];
135 else
136 newoff = hashp->BSIZE;
137 pairlen = newoff - bp[ndx + 1];
138
139 if (ndx != (n - 1)) {
140 /* Hard Case -- need to shuffle keys */
141 int i;
142 char *src = bufp->page + (int)OFFSET(bp);
143 char *dst = src + (int)pairlen;
144 memmove(dst, src, bp[ndx + 1] - OFFSET(bp));
145
146 /* Now adjust the pointers */
147 for (i = ndx + 2; i <= n; i += 2) {
148 if (bp[i + 1] == OVFLPAGE) {
149 bp[i - 2] = bp[i];
150 bp[i - 1] = bp[i + 1];
151 } else {
152 bp[i - 2] = bp[i] + pairlen;
153 bp[i - 1] = bp[i + 1] + pairlen;
154 }
155 }
156 }
157 /* Finally adjust the page data */
158 bp[n] = OFFSET(bp) + pairlen;
159 bp[n - 1] = bp[n + 1] + pairlen + 2 * sizeof(u_int16_t);
160 bp[0] = n - 2;
161 hashp->NKEYS--;
162
163 bufp->flags |= BUF_MOD;
164 return (0);
165 }
166 /*
167 * Returns:
168 * 0 ==> OK
169 * -1 ==> Error
170 */
171 int
__split_page(HTAB * hashp,u_int32_t obucket,u_int32_t nbucket)172 __split_page(HTAB *hashp, u_int32_t obucket, u_int32_t nbucket)
173 {
174 BUFHEAD *new_bufp, *old_bufp;
175 u_int16_t *ino;
176 char *np;
177 DBT key, val;
178 int n, ndx, retval;
179 u_int16_t copyto, diff, off, moved;
180 char *op;
181
182 copyto = (u_int16_t)hashp->BSIZE;
183 off = (u_int16_t)hashp->BSIZE;
184 old_bufp = __get_buf(hashp, obucket, NULL, 0);
185 if (old_bufp == NULL)
186 return (-1);
187 new_bufp = __get_buf(hashp, nbucket, NULL, 0);
188 if (new_bufp == NULL)
189 return (-1);
190
191 old_bufp->flags |= (BUF_MOD | BUF_PIN);
192 new_bufp->flags |= (BUF_MOD | BUF_PIN);
193
194 ino = (u_int16_t *)(op = old_bufp->page);
195 np = new_bufp->page;
196
197 moved = 0;
198
199 for (n = 1, ndx = 1; n < ino[0]; n += 2) {
200 if (ino[n + 1] < REAL_KEY) {
201 retval = ugly_split(hashp, obucket, old_bufp, new_bufp,
202 (int)copyto, (int)moved);
203 old_bufp->flags &= ~BUF_PIN;
204 new_bufp->flags &= ~BUF_PIN;
205 return (retval);
206
207 }
208 key.data = (u_char *)op + ino[n];
209 key.size = off - ino[n];
210
211 if (__call_hash(hashp, key.data, key.size) == obucket) {
212 /* Don't switch page */
213 diff = copyto - off;
214 if (diff) {
215 copyto = ino[n + 1] + diff;
216 memmove(op + copyto, op + ino[n + 1],
217 off - ino[n + 1]);
218 ino[ndx] = copyto + ino[n] - ino[n + 1];
219 ino[ndx + 1] = copyto;
220 } else
221 copyto = ino[n + 1];
222 ndx += 2;
223 } else {
224 /* Switch page */
225 val.data = (u_char *)op + ino[n + 1];
226 val.size = ino[n] - ino[n + 1];
227 putpair(np, &key, &val);
228 moved += 2;
229 }
230
231 off = ino[n + 1];
232 }
233
234 /* Now clean up the page */
235 ino[0] -= moved;
236 FREESPACE(ino) = copyto - sizeof(u_int16_t) * (ino[0] + 3);
237 OFFSET(ino) = copyto;
238
239 #ifdef DEBUG3
240 (void)fprintf(stderr, "split %d/%d\n",
241 ((u_int16_t *)np)[0] / 2,
242 ((u_int16_t *)op)[0] / 2);
243 #endif
244 /* unpin both pages */
245 old_bufp->flags &= ~BUF_PIN;
246 new_bufp->flags &= ~BUF_PIN;
247 return (0);
248 }
249
250 /*
251 * Called when we encounter an overflow or big key/data page during split
252 * handling. This is special cased since we have to begin checking whether
253 * the key/data pairs fit on their respective pages and because we may need
254 * overflow pages for both the old and new pages.
255 *
256 * The first page might be a page with regular key/data pairs in which case
257 * we have a regular overflow condition and just need to go on to the next
258 * page or it might be a big key/data pair in which case we need to fix the
259 * big key/data pair.
260 *
261 * Returns:
262 * 0 ==> success
263 * -1 ==> failure
264 */
265 static int
ugly_split(HTAB * hashp,u_int32_t obucket,BUFHEAD * old_bufp,BUFHEAD * new_bufp,int copyto,int moved)266 ugly_split(HTAB *hashp,
267 u_int32_t obucket, /* Same as __split_page. */
268 BUFHEAD *old_bufp,
269 BUFHEAD *new_bufp,
270 int copyto, /* First byte on page which contains key/data values. */
271 int moved) /* Number of pairs moved to new page. */
272 {
273 BUFHEAD *bufp; /* Buffer header for ino */
274 u_int16_t *ino; /* Page keys come off of */
275 u_int16_t *np; /* New page */
276 u_int16_t *op; /* Page keys go on to if they aren't moving */
277
278 BUFHEAD *last_bfp; /* Last buf header OVFL needing to be freed */
279 DBT key, val;
280 SPLIT_RETURN ret;
281 u_int16_t n, off, ov_addr, scopyto;
282 char *cino; /* Character value of ino */
283
284 bufp = old_bufp;
285 ino = (u_int16_t *)old_bufp->page;
286 np = (u_int16_t *)new_bufp->page;
287 op = (u_int16_t *)old_bufp->page;
288 last_bfp = NULL;
289 scopyto = (u_int16_t)copyto; /* ANSI */
290
291 n = ino[0] - 1;
292 while (n < ino[0]) {
293 if (ino[2] < REAL_KEY && ino[2] != OVFLPAGE) {
294 if (__big_split(hashp, old_bufp,
295 new_bufp, bufp, bufp->addr, obucket, &ret))
296 return (-1);
297 old_bufp = ret.oldp;
298 if (!old_bufp)
299 return (-1);
300 op = (u_int16_t *)old_bufp->page;
301 new_bufp = ret.newp;
302 if (!new_bufp)
303 return (-1);
304 np = (u_int16_t *)new_bufp->page;
305 bufp = ret.nextp;
306 if (!bufp)
307 return (0);
308 cino = (char *)bufp->page;
309 ino = (u_int16_t *)cino;
310 last_bfp = ret.nextp;
311 } else if (ino[n + 1] == OVFLPAGE) {
312 ov_addr = ino[n];
313 /*
314 * Fix up the old page -- the extra 2 are the fields
315 * which contained the overflow information.
316 */
317 ino[0] -= (moved + 2);
318 FREESPACE(ino) =
319 scopyto - sizeof(u_int16_t) * (ino[0] + 3);
320 OFFSET(ino) = scopyto;
321
322 bufp = __get_buf(hashp, ov_addr, bufp, 0);
323 if (!bufp)
324 return (-1);
325
326 ino = (u_int16_t *)bufp->page;
327 n = 1;
328 scopyto = hashp->BSIZE;
329 moved = 0;
330
331 if (last_bfp)
332 __free_ovflpage(hashp, last_bfp);
333 last_bfp = bufp;
334 }
335 /* Move regular sized pairs of there are any */
336 off = hashp->BSIZE;
337 for (n = 1; (n < ino[0]) && (ino[n + 1] >= REAL_KEY); n += 2) {
338 cino = (char *)ino;
339 key.data = (u_char *)cino + ino[n];
340 key.size = off - ino[n];
341 val.data = (u_char *)cino + ino[n + 1];
342 val.size = ino[n] - ino[n + 1];
343 off = ino[n + 1];
344
345 if (__call_hash(hashp, key.data, key.size) == obucket) {
346 /* Keep on old page */
347 if (PAIRFITS(op, (&key), (&val)))
348 putpair((char *)op, &key, &val);
349 else {
350 old_bufp =
351 __add_ovflpage(hashp, old_bufp);
352 if (!old_bufp)
353 return (-1);
354 op = (u_int16_t *)old_bufp->page;
355 putpair((char *)op, &key, &val);
356 }
357 old_bufp->flags |= BUF_MOD;
358 } else {
359 /* Move to new page */
360 if (PAIRFITS(np, (&key), (&val)))
361 putpair((char *)np, &key, &val);
362 else {
363 new_bufp =
364 __add_ovflpage(hashp, new_bufp);
365 if (!new_bufp)
366 return (-1);
367 np = (u_int16_t *)new_bufp->page;
368 putpair((char *)np, &key, &val);
369 }
370 new_bufp->flags |= BUF_MOD;
371 }
372 }
373 }
374 if (last_bfp)
375 __free_ovflpage(hashp, last_bfp);
376 return (0);
377 }
378
379 /*
380 * Add the given pair to the page
381 *
382 * Returns:
383 * 0 ==> OK
384 * 1 ==> failure
385 */
386 int
__addel(HTAB * hashp,BUFHEAD * bufp,const DBT * key,const DBT * val)387 __addel(HTAB *hashp, BUFHEAD *bufp, const DBT *key, const DBT *val)
388 {
389 u_int16_t *bp, *sop;
390 int do_expand;
391
392 bp = (u_int16_t *)bufp->page;
393 do_expand = 0;
394 while (bp[0] && (bp[2] < REAL_KEY || bp[bp[0]] < REAL_KEY))
395 /* Exception case */
396 if (bp[2] == FULL_KEY_DATA && bp[0] == 2)
397 /* This is the last page of a big key/data pair
398 and we need to add another page */
399 break;
400 else if (bp[2] < REAL_KEY && bp[bp[0]] != OVFLPAGE) {
401 bufp = __get_buf(hashp, bp[bp[0] - 1], bufp, 0);
402 if (!bufp)
403 return (-1);
404 bp = (u_int16_t *)bufp->page;
405 } else if (bp[bp[0]] != OVFLPAGE) {
406 /* Short key/data pairs, no more pages */
407 break;
408 } else {
409 /* Try to squeeze key on this page */
410 if (bp[2] >= REAL_KEY &&
411 FREESPACE(bp) >= PAIRSIZE(key, val)) {
412 squeeze_key(bp, key, val);
413 goto stats;
414 } else {
415 bufp = __get_buf(hashp, bp[bp[0] - 1], bufp, 0);
416 if (!bufp)
417 return (-1);
418 bp = (u_int16_t *)bufp->page;
419 }
420 }
421
422 if (PAIRFITS(bp, key, val))
423 putpair(bufp->page, key, val);
424 else {
425 do_expand = 1;
426 bufp = __add_ovflpage(hashp, bufp);
427 if (!bufp)
428 return (-1);
429 sop = (u_int16_t *)bufp->page;
430
431 if (PAIRFITS(sop, key, val))
432 putpair((char *)sop, key, val);
433 else
434 if (__big_insert(hashp, bufp, key, val))
435 return (-1);
436 }
437 stats:
438 bufp->flags |= BUF_MOD;
439 /*
440 * If the average number of keys per bucket exceeds the fill factor,
441 * expand the table.
442 */
443 hashp->NKEYS++;
444 if (do_expand ||
445 (hashp->NKEYS / (hashp->MAX_BUCKET + 1) > hashp->FFACTOR))
446 return (__expand_table(hashp));
447 return (0);
448 }
449
450 /*
451 *
452 * Returns:
453 * pointer on success
454 * NULL on error
455 */
456 BUFHEAD *
__add_ovflpage(HTAB * hashp,BUFHEAD * bufp)457 __add_ovflpage(HTAB *hashp, BUFHEAD *bufp)
458 {
459 u_int16_t *sp, ndx, ovfl_num;
460 #ifdef DEBUG1
461 int tmp1, tmp2;
462 #endif
463 sp = (u_int16_t *)bufp->page;
464
465 /* Check if we are dynamically determining the fill factor */
466 if (hashp->FFACTOR == DEF_FFACTOR) {
467 hashp->FFACTOR = sp[0] >> 1;
468 if (hashp->FFACTOR < MIN_FFACTOR)
469 hashp->FFACTOR = MIN_FFACTOR;
470 }
471 bufp->flags |= BUF_MOD;
472 ovfl_num = overflow_page(hashp);
473 #ifdef DEBUG1
474 tmp1 = bufp->addr;
475 tmp2 = bufp->ovfl ? bufp->ovfl->addr : 0;
476 #endif
477 if (!ovfl_num || !(bufp->ovfl = __get_buf(hashp, ovfl_num, bufp, 1)))
478 return (NULL);
479 bufp->ovfl->flags |= BUF_MOD;
480 #ifdef DEBUG1
481 (void)fprintf(stderr, "ADDOVFLPAGE: %d->ovfl was %d is now %d\n",
482 tmp1, tmp2, bufp->ovfl->addr);
483 #endif
484 ndx = sp[0];
485 /*
486 * Since a pair is allocated on a page only if there's room to add
487 * an overflow page, we know that the OVFL information will fit on
488 * the page.
489 */
490 sp[ndx + 4] = OFFSET(sp);
491 sp[ndx + 3] = FREESPACE(sp) - OVFLSIZE;
492 sp[ndx + 1] = ovfl_num;
493 sp[ndx + 2] = OVFLPAGE;
494 sp[0] = ndx + 2;
495 #ifdef HASH_STATISTICS
496 hash_overflows++;
497 #endif
498 return (bufp->ovfl);
499 }
500
501 /*
502 * Returns:
503 * 0 indicates SUCCESS
504 * -1 indicates FAILURE
505 */
506 int
__get_page(HTAB * hashp,char * p,u_int32_t bucket,int is_bucket,int is_disk,int is_bitmap)507 __get_page(HTAB *hashp, char *p, u_int32_t bucket, int is_bucket, int is_disk,
508 int is_bitmap)
509 {
510 int fd, page, size, rsize;
511 u_int16_t *bp;
512
513 fd = hashp->fp;
514 size = hashp->BSIZE;
515
516 if ((fd == -1) || !is_disk) {
517 PAGE_INIT(p);
518 return (0);
519 }
520 if (is_bucket)
521 page = BUCKET_TO_PAGE(bucket);
522 else
523 page = OADDR_TO_PAGE(bucket);
524 if ((rsize = pread(fd, p, size, (off_t)page << hashp->BSHIFT)) == -1)
525 return (-1);
526 bp = (u_int16_t *)p;
527 if (!rsize)
528 bp[0] = 0; /* We hit the EOF, so initialize a new page */
529 else
530 if (rsize != size) {
531 errno = EFTYPE;
532 return (-1);
533 }
534 if (!is_bitmap && !bp[0]) {
535 PAGE_INIT(p);
536 } else
537 if (hashp->LORDER != BYTE_ORDER) {
538 int i, max;
539
540 if (is_bitmap) {
541 max = hashp->BSIZE >> 2; /* divide by 4 */
542 for (i = 0; i < max; i++)
543 M_32_SWAP(((int *)p)[i]);
544 } else {
545 M_16_SWAP(bp[0]);
546 max = bp[0] + 2;
547 for (i = 1; i <= max; i++)
548 M_16_SWAP(bp[i]);
549 }
550 }
551 return (0);
552 }
553
554 /*
555 * Write page p to disk
556 *
557 * Returns:
558 * 0 ==> OK
559 * -1 ==>failure
560 */
561 int
__put_page(HTAB * hashp,char * p,u_int32_t bucket,int is_bucket,int is_bitmap)562 __put_page(HTAB *hashp, char *p, u_int32_t bucket, int is_bucket, int is_bitmap)
563 {
564 int fd, page, size, wsize;
565
566 size = hashp->BSIZE;
567 if ((hashp->fp == -1) && open_temp(hashp))
568 return (-1);
569 fd = hashp->fp;
570
571 if (hashp->LORDER != BYTE_ORDER) {
572 int i, max;
573
574 if (is_bitmap) {
575 max = hashp->BSIZE >> 2; /* divide by 4 */
576 for (i = 0; i < max; i++)
577 M_32_SWAP(((int *)p)[i]);
578 } else {
579 max = ((u_int16_t *)p)[0] + 2;
580 for (i = 0; i <= max; i++)
581 M_16_SWAP(((u_int16_t *)p)[i]);
582 }
583 }
584 if (is_bucket)
585 page = BUCKET_TO_PAGE(bucket);
586 else
587 page = OADDR_TO_PAGE(bucket);
588 if ((wsize = pwrite(fd, p, size, (off_t)page << hashp->BSHIFT)) == -1)
589 /* Errno is set */
590 return (-1);
591 if (wsize != size) {
592 errno = EFTYPE;
593 return (-1);
594 }
595 return (0);
596 }
597
598 #define BYTE_MASK ((1 << INT_BYTE_SHIFT) -1)
599 /*
600 * Initialize a new bitmap page. Bitmap pages are left in memory
601 * once they are read in.
602 */
603 int
__ibitmap(HTAB * hashp,int pnum,int nbits,int ndx)604 __ibitmap(HTAB *hashp, int pnum, int nbits, int ndx)
605 {
606 u_int32_t *ip;
607 int clearbytes, clearints;
608
609 if ((ip = (u_int32_t *)malloc(hashp->BSIZE)) == NULL)
610 return (1);
611 hashp->nmaps++;
612 clearints = ((nbits - 1) >> INT_BYTE_SHIFT) + 1;
613 clearbytes = clearints << INT_TO_BYTE;
614 (void)memset((char *)ip, 0, clearbytes);
615 (void)memset(((char *)ip) + clearbytes, 0xFF,
616 hashp->BSIZE - clearbytes);
617 ip[clearints - 1] = ALL_SET << (nbits & BYTE_MASK);
618 SETBIT(ip, 0);
619 hashp->BITMAPS[ndx] = (u_int16_t)pnum;
620 hashp->mapp[ndx] = ip;
621 return (0);
622 }
623
624 static u_int32_t
first_free(u_int32_t map)625 first_free(u_int32_t map)
626 {
627 u_int32_t i, mask;
628
629 mask = 0x1;
630 for (i = 0; i < BITS_PER_MAP; i++) {
631 if (!(mask & map))
632 return (i);
633 mask = mask << 1;
634 }
635 return (i);
636 }
637
638 static u_int16_t
overflow_page(HTAB * hashp)639 overflow_page(HTAB *hashp)
640 {
641 u_int32_t *freep = NULL;
642 int max_free, offset, splitnum;
643 u_int16_t addr;
644 int bit, first_page, free_bit, free_page, i, in_use_bits, j;
645 #ifdef DEBUG2
646 int tmp1, tmp2;
647 #endif
648 splitnum = hashp->OVFL_POINT;
649 max_free = hashp->SPARES[splitnum];
650
651 free_page = (max_free - 1) >> (hashp->BSHIFT + BYTE_SHIFT);
652 free_bit = (max_free - 1) & ((hashp->BSIZE << BYTE_SHIFT) - 1);
653
654 /* Look through all the free maps to find the first free block */
655 first_page = hashp->LAST_FREED >>(hashp->BSHIFT + BYTE_SHIFT);
656 for ( i = first_page; i <= free_page; i++ ) {
657 if (!(freep = (u_int32_t *)hashp->mapp[i]) &&
658 !(freep = fetch_bitmap(hashp, i)))
659 return (0);
660 if (i == free_page)
661 in_use_bits = free_bit;
662 else
663 in_use_bits = (hashp->BSIZE << BYTE_SHIFT) - 1;
664
665 if (i == first_page) {
666 bit = hashp->LAST_FREED &
667 ((hashp->BSIZE << BYTE_SHIFT) - 1);
668 j = bit / BITS_PER_MAP;
669 bit = bit & ~(BITS_PER_MAP - 1);
670 } else {
671 bit = 0;
672 j = 0;
673 }
674 for (; bit <= in_use_bits; j++, bit += BITS_PER_MAP)
675 if (freep[j] != ALL_SET)
676 goto found;
677 }
678
679 /* No Free Page Found */
680 hashp->LAST_FREED = hashp->SPARES[splitnum];
681 hashp->SPARES[splitnum]++;
682 offset = hashp->SPARES[splitnum] -
683 (splitnum ? hashp->SPARES[splitnum - 1] : 0);
684
685 #define OVMSG "HASH: Out of overflow pages. Increase page size\n"
686 if (offset > SPLITMASK) {
687 if (++splitnum >= NCACHED) {
688 (void)write(STDERR_FILENO, OVMSG, sizeof(OVMSG) - 1);
689 errno = EFBIG;
690 return (0);
691 }
692 hashp->OVFL_POINT = splitnum;
693 hashp->SPARES[splitnum] = hashp->SPARES[splitnum-1];
694 hashp->SPARES[splitnum-1]--;
695 offset = 1;
696 }
697
698 /* Check if we need to allocate a new bitmap page */
699 if (free_bit == (hashp->BSIZE << BYTE_SHIFT) - 1) {
700 free_page++;
701 if (free_page >= NCACHED) {
702 (void)write(STDERR_FILENO, OVMSG, sizeof(OVMSG) - 1);
703 errno = EFBIG;
704 return (0);
705 }
706 /*
707 * This is tricky. The 1 indicates that you want the new page
708 * allocated with 1 clear bit. Actually, you are going to
709 * allocate 2 pages from this map. The first is going to be
710 * the map page, the second is the overflow page we were
711 * looking for. The init_bitmap routine automatically, sets
712 * the first bit of itself to indicate that the bitmap itself
713 * is in use. We would explicitly set the second bit, but
714 * don't have to if we tell init_bitmap not to leave it clear
715 * in the first place.
716 */
717 if (__ibitmap(hashp,
718 (int)OADDR_OF(splitnum, offset), 1, free_page))
719 return (0);
720 hashp->SPARES[splitnum]++;
721 #ifdef DEBUG2
722 free_bit = 2;
723 #endif
724 offset++;
725 if (offset > SPLITMASK) {
726 if (++splitnum >= NCACHED) {
727 (void)write(STDERR_FILENO, OVMSG,
728 sizeof(OVMSG) - 1);
729 errno = EFBIG;
730 return (0);
731 }
732 hashp->OVFL_POINT = splitnum;
733 hashp->SPARES[splitnum] = hashp->SPARES[splitnum-1];
734 hashp->SPARES[splitnum-1]--;
735 offset = 0;
736 }
737 } else {
738 /*
739 * Free_bit addresses the last used bit. Bump it to address
740 * the first available bit.
741 */
742 free_bit++;
743 SETBIT(freep, free_bit);
744 }
745
746 /* Calculate address of the new overflow page */
747 addr = OADDR_OF(splitnum, offset);
748 #ifdef DEBUG2
749 (void)fprintf(stderr, "OVERFLOW_PAGE: ADDR: %d BIT: %d PAGE %d\n",
750 addr, free_bit, free_page);
751 #endif
752 return (addr);
753
754 found:
755 bit = bit + first_free(freep[j]);
756 SETBIT(freep, bit);
757 #ifdef DEBUG2
758 tmp1 = bit;
759 tmp2 = i;
760 #endif
761 /*
762 * Bits are addressed starting with 0, but overflow pages are addressed
763 * beginning at 1. Bit is a bit addressnumber, so we need to increment
764 * it to convert it to a page number.
765 */
766 bit = 1 + bit + (i * (hashp->BSIZE << BYTE_SHIFT));
767 if (bit >= hashp->LAST_FREED)
768 hashp->LAST_FREED = bit - 1;
769
770 /* Calculate the split number for this page */
771 for (i = 0; (i < splitnum) && (bit > hashp->SPARES[i]); i++);
772 offset = (i ? bit - hashp->SPARES[i - 1] : bit);
773 if (offset >= SPLITMASK) {
774 (void)write(STDERR_FILENO, OVMSG, sizeof(OVMSG) - 1);
775 errno = EFBIG;
776 return (0); /* Out of overflow pages */
777 }
778 addr = OADDR_OF(i, offset);
779 #ifdef DEBUG2
780 (void)fprintf(stderr, "OVERFLOW_PAGE: ADDR: %d BIT: %d PAGE %d\n",
781 addr, tmp1, tmp2);
782 #endif
783
784 /* Allocate and return the overflow page */
785 return (addr);
786 }
787
788 /*
789 * Mark this overflow page as free.
790 */
791 void
__free_ovflpage(HTAB * hashp,BUFHEAD * obufp)792 __free_ovflpage(HTAB *hashp, BUFHEAD *obufp)
793 {
794 u_int16_t addr;
795 u_int32_t *freep;
796 int bit_address, free_page, free_bit;
797 u_int16_t ndx;
798
799 addr = obufp->addr;
800 #ifdef DEBUG1
801 (void)fprintf(stderr, "Freeing %d\n", addr);
802 #endif
803 ndx = (((u_int16_t)addr) >> SPLITSHIFT);
804 bit_address =
805 (ndx ? hashp->SPARES[ndx - 1] : 0) + (addr & SPLITMASK) - 1;
806 if (bit_address < hashp->LAST_FREED)
807 hashp->LAST_FREED = bit_address;
808 free_page = (bit_address >> (hashp->BSHIFT + BYTE_SHIFT));
809 free_bit = bit_address & ((hashp->BSIZE << BYTE_SHIFT) - 1);
810
811 if (!(freep = hashp->mapp[free_page]))
812 freep = fetch_bitmap(hashp, free_page);
813 #ifdef DEBUG
814 /*
815 * This had better never happen. It means we tried to read a bitmap
816 * that has already had overflow pages allocated off it, and we
817 * failed to read it from the file.
818 */
819 if (!freep)
820 assert(0);
821 #endif
822 CLRBIT(freep, free_bit);
823 #ifdef DEBUG2
824 (void)fprintf(stderr, "FREE_OVFLPAGE: ADDR: %d BIT: %d PAGE %d\n",
825 obufp->addr, free_bit, free_page);
826 #endif
827 __reclaim_buf(hashp, obufp);
828 }
829
830 /*
831 * Returns:
832 * 0 success
833 * -1 failure
834 */
835 static int
open_temp(HTAB * hashp)836 open_temp(HTAB *hashp)
837 {
838 sigset_t set, oset;
839 char *envtmp = NULL;
840 char path[MAXPATHLEN];
841
842 if (issetugid() == 0)
843 envtmp = getenv("TMPDIR");
844 (void)snprintf(path,
845 sizeof(path), "%s/_hash.XXXXXX", envtmp ? envtmp : "/tmp");
846
847 /* Block signals; make sure file goes away at process exit. */
848 (void)sigfillset(&set);
849 (void)sigprocmask(SIG_BLOCK, &set, &oset);
850 if ((hashp->fp = mkstemp(path)) != -1) {
851 (void)unlink(path);
852 (void)fcntl(hashp->fp, F_SETFD, 1);
853 }
854 (void)sigprocmask(SIG_SETMASK, &oset, (sigset_t *)NULL);
855 return (hashp->fp != -1 ? 0 : -1);
856 }
857
858 /*
859 * We have to know that the key will fit, but the last entry on the page is
860 * an overflow pair, so we need to shift things.
861 */
862 static void
squeeze_key(u_int16_t * sp,const DBT * key,const DBT * val)863 squeeze_key(u_int16_t *sp, const DBT *key, const DBT *val)
864 {
865 char *p;
866 u_int16_t free_space, n, off, pageno;
867
868 p = (char *)sp;
869 n = sp[0];
870 free_space = FREESPACE(sp);
871 off = OFFSET(sp);
872
873 pageno = sp[n - 1];
874 off -= key->size;
875 sp[n - 1] = off;
876 memmove(p + off, key->data, key->size);
877 off -= val->size;
878 sp[n] = off;
879 memmove(p + off, val->data, val->size);
880 sp[0] = n + 2;
881 sp[n + 1] = pageno;
882 sp[n + 2] = OVFLPAGE;
883 FREESPACE(sp) = free_space - PAIRSIZE(key, val);
884 OFFSET(sp) = off;
885 }
886
887 static u_int32_t *
fetch_bitmap(HTAB * hashp,int ndx)888 fetch_bitmap(HTAB *hashp, int ndx)
889 {
890 if (ndx >= hashp->nmaps)
891 return (NULL);
892 if ((hashp->mapp[ndx] = (u_int32_t *)malloc(hashp->BSIZE)) == NULL)
893 return (NULL);
894 if (__get_page(hashp,
895 (char *)hashp->mapp[ndx], hashp->BITMAPS[ndx], 0, 1, 1)) {
896 free(hashp->mapp[ndx]);
897 return (NULL);
898 }
899 return (hashp->mapp[ndx]);
900 }
901
902 #ifdef DEBUG4
903 int
print_chain(int addr)904 print_chain(int addr)
905 {
906 BUFHEAD *bufp;
907 short *bp, oaddr;
908
909 (void)fprintf(stderr, "%d ", addr);
910 bufp = __get_buf(hashp, addr, NULL, 0);
911 bp = (short *)bufp->page;
912 while (bp[0] && ((bp[bp[0]] == OVFLPAGE) ||
913 ((bp[0] > 2) && bp[2] < REAL_KEY))) {
914 oaddr = bp[bp[0] - 1];
915 (void)fprintf(stderr, "%d ", (int)oaddr);
916 bufp = __get_buf(hashp, (int)oaddr, bufp, 0);
917 bp = (short *)bufp->page;
918 }
919 (void)fprintf(stderr, "\n");
920 }
921 #endif
922