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1 /*-
2 * Copyright (c) 1990, 1993, 1994
3 * The Regents of the University of California. All rights reserved.
4 *
5 * This code is derived from software contributed to Berkeley by
6 * Margo Seltzer.
7 *
8 * Redistribution and use in source and binary forms, with or without
9 * modification, are permitted provided that the following conditions
10 * are met:
11 * 1. Redistributions of source code must retain the above copyright
12 * notice, this list of conditions and the following disclaimer.
13 * 2. Redistributions in binary form must reproduce the above copyright
14 * notice, this list of conditions and the following disclaimer in the
15 * documentation and/or other materials provided with the distribution.
16 * 4. Neither the name of the University nor the names of its contributors
17 * may be used to endorse or promote products derived from this software
18 * without specific prior written permission.
19 *
20 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
21 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
22 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
23 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
24 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
25 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
26 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
27 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
28 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
29 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
30 * SUCH DAMAGE.
31 */
32
33 #if defined(LIBC_SCCS) && !defined(lint)
34 static char sccsid[] = "@(#)hash_page.c 8.7 (Berkeley) 8/16/94";
35 #endif /* LIBC_SCCS and not lint */
36 #include <sys/cdefs.h>
37 __FBSDID("$FreeBSD: src/lib/libc/db/hash/hash_page.c,v 1.16 2009/03/28 06:30:43 delphij Exp $");
38
39 /*
40 * PACKAGE: hashing
41 *
42 * DESCRIPTION:
43 * Page manipulation for hashing package.
44 *
45 * ROUTINES:
46 *
47 * External
48 * __get_page
49 * __add_ovflpage
50 * Internal
51 * overflow_page
52 * open_temp
53 */
54
55 #include "namespace.h"
56 #include <sys/param.h>
57
58 #include <errno.h>
59 #include <fcntl.h>
60 #include <signal.h>
61 #include <stdio.h>
62 #include <stdlib.h>
63 #include <string.h>
64 #include <unistd.h>
65 #ifdef DEBUG
66 #include <assert.h>
67 #endif
68 #include "un-namespace.h"
69
70 #include <db.h>
71 #include "hash.h"
72 #include "page.h"
73 #include "hash_extern.h"
74
75 static u_int32_t *fetch_bitmap(HTAB *, int);
76 static u_int32_t first_free(u_int32_t);
77 static int open_temp(HTAB *);
78 static u_int16_t overflow_page(HTAB *);
79 static void putpair(char *, const DBT *, const DBT *);
80 static void squeeze_key(u_int16_t *, const DBT *, const DBT *);
81 static int ugly_split(HTAB *, u_int32_t, BUFHEAD *, BUFHEAD *, int, int);
82
83 #define PAGE_INIT(P) { \
84 ((u_int16_t *)(P))[0] = 0; \
85 ((u_int16_t *)(P))[1] = hashp->BSIZE - 3 * sizeof(u_int16_t); \
86 ((u_int16_t *)(P))[2] = hashp->BSIZE; \
87 }
88
89 /*
90 * This is called AFTER we have verified that there is room on the page for
91 * the pair (PAIRFITS has returned true) so we go right ahead and start moving
92 * stuff on.
93 */
94 static void
95 putpair(char *p, const DBT *key, const DBT *val)
96 {
97 u_int16_t *bp, n, off;
98
99 bp = (u_int16_t *)p;
100
101 /* Enter the key first. */
102 n = bp[0];
103
104 off = OFFSET(bp) - key->size;
105 memmove(p + off, key->data, key->size);
106 bp[++n] = off;
107
108 /* Now the data. */
109 off -= val->size;
110 memmove(p + off, val->data, val->size);
111 bp[++n] = off;
112
113 /* Adjust page info. */
114 bp[0] = n;
115 bp[n + 1] = off - ((n + 3) * sizeof(u_int16_t));
116 bp[n + 2] = off;
117 }
118
119 /*
120 * Returns:
121 * 0 OK
122 * -1 error
123 */
124 int
125 __delpair(HTAB *hashp, BUFHEAD *bufp, int ndx)
126 {
127 u_int16_t *bp, newoff, pairlen;
128 int n;
129
130 bp = (u_int16_t *)bufp->page;
131 n = bp[0];
132
133 if (bp[ndx + 1] < REAL_KEY)
134 return (__big_delete(hashp, bufp));
135 if (ndx != 1)
136 newoff = bp[ndx - 1];
137 else
138 newoff = hashp->BSIZE;
139 pairlen = newoff - bp[ndx + 1];
140
141 if (ndx != (n - 1)) {
142 /* Hard Case -- need to shuffle keys */
143 int i;
144 char *src = bufp->page + (int)OFFSET(bp);
145 char *dst = src + (int)pairlen;
146 memmove(dst, src, bp[ndx + 1] - OFFSET(bp));
147
148 /* Now adjust the pointers */
149 for (i = ndx + 2; i <= n; i += 2) {
150 if (bp[i + 1] == OVFLPAGE) {
151 bp[i - 2] = bp[i];
152 bp[i - 1] = bp[i + 1];
153 } else {
154 bp[i - 2] = bp[i] + pairlen;
155 bp[i - 1] = bp[i + 1] + pairlen;
156 }
157 }
158 if (ndx == hashp->cndx) {
159 /*
160 * We just removed pair we were "pointing" to.
161 * By moving back the cndx we ensure subsequent
162 * hash_seq() calls won't skip over any entries.
163 */
164 hashp->cndx -= 2;
165 }
166 }
167 /* Finally adjust the page data */
168 bp[n] = OFFSET(bp) + pairlen;
169 bp[n - 1] = bp[n + 1] + pairlen + 2 * sizeof(u_int16_t);
170 bp[0] = n - 2;
171 hashp->NKEYS--;
172
173 bufp->flags |= BUF_MOD;
174 return (0);
175 }
176 /*
177 * Returns:
178 * 0 ==> OK
179 * -1 ==> Error
180 */
181 int
182 __split_page(HTAB *hashp, u_int32_t obucket, u_int32_t nbucket)
183 {
184 BUFHEAD *new_bufp, *old_bufp;
185 u_int16_t *ino;
186 char *np;
187 DBT key, val;
188 int n, ndx, retval;
189 u_int16_t copyto, diff, off, moved;
190 char *op;
191
192 copyto = (u_int16_t)hashp->BSIZE;
193 off = (u_int16_t)hashp->BSIZE;
194 old_bufp = __get_buf(hashp, obucket, NULL, 0);
195 if (old_bufp == NULL)
196 return (-1);
197 new_bufp = __get_buf(hashp, nbucket, NULL, 0);
198 if (new_bufp == NULL)
199 return (-1);
200
201 old_bufp->flags |= (BUF_MOD | BUF_PIN);
202 new_bufp->flags |= (BUF_MOD | BUF_PIN);
203
204 ino = (u_int16_t *)(op = old_bufp->page);
205 np = new_bufp->page;
206
207 moved = 0;
208
209 for (n = 1, ndx = 1; n < ino[0]; n += 2) {
210 if (ino[n + 1] < REAL_KEY) {
211 retval = ugly_split(hashp, obucket, old_bufp, new_bufp,
212 (int)copyto, (int)moved);
213 old_bufp->flags &= ~BUF_PIN;
214 new_bufp->flags &= ~BUF_PIN;
215 return (retval);
216
217 }
218 key.data = (u_char *)op + ino[n];
219 key.size = off - ino[n];
220
221 if (__call_hash(hashp, key.data, key.size) == obucket) {
222 /* Don't switch page */
223 diff = copyto - off;
224 if (diff) {
225 copyto = ino[n + 1] + diff;
226 memmove(op + copyto, op + ino[n + 1],
227 off - ino[n + 1]);
228 ino[ndx] = copyto + ino[n] - ino[n + 1];
229 ino[ndx + 1] = copyto;
230 } else
231 copyto = ino[n + 1];
232 ndx += 2;
233 } else {
234 /* Switch page */
235 val.data = (u_char *)op + ino[n + 1];
236 val.size = ino[n] - ino[n + 1];
237 putpair(np, &key, &val);
238 moved += 2;
239 }
240
241 off = ino[n + 1];
242 }
243
244 /* Now clean up the page */
245 ino[0] -= moved;
246 FREESPACE(ino) = copyto - sizeof(u_int16_t) * (ino[0] + 3);
247 OFFSET(ino) = copyto;
248
249 #ifdef DEBUG3
250 (void)fprintf(stderr, "split %d/%d\n",
251 ((u_int16_t *)np)[0] / 2,
252 ((u_int16_t *)op)[0] / 2);
253 #endif
254 /* unpin both pages */
255 old_bufp->flags &= ~BUF_PIN;
256 new_bufp->flags &= ~BUF_PIN;
257 return (0);
258 }
259
260 /*
261 * Called when we encounter an overflow or big key/data page during split
262 * handling. This is special cased since we have to begin checking whether
263 * the key/data pairs fit on their respective pages and because we may need
264 * overflow pages for both the old and new pages.
265 *
266 * The first page might be a page with regular key/data pairs in which case
267 * we have a regular overflow condition and just need to go on to the next
268 * page or it might be a big key/data pair in which case we need to fix the
269 * big key/data pair.
270 *
271 * Returns:
272 * 0 ==> success
273 * -1 ==> failure
274 */
275 static int
276 ugly_split(HTAB *hashp,
277 u_int32_t obucket, /* Same as __split_page. */
278 BUFHEAD *old_bufp,
279 BUFHEAD *new_bufp,
280 int copyto, /* First byte on page which contains key/data values. */
281 int moved) /* Number of pairs moved to new page. */
282 {
283 BUFHEAD *bufp; /* Buffer header for ino */
284 u_int16_t *ino; /* Page keys come off of */
285 u_int16_t *np; /* New page */
286 u_int16_t *op; /* Page keys go on to if they aren't moving */
287
288 BUFHEAD *last_bfp; /* Last buf header OVFL needing to be freed */
289 DBT key, val;
290 SPLIT_RETURN ret;
291 u_int16_t n, off, ov_addr, scopyto;
292 char *cino; /* Character value of ino */
293
294 bufp = old_bufp;
295 ino = (u_int16_t *)old_bufp->page;
296 np = (u_int16_t *)new_bufp->page;
297 op = (u_int16_t *)old_bufp->page;
298 last_bfp = NULL;
299 scopyto = (u_int16_t)copyto; /* ANSI */
300
301 n = ino[0] - 1;
302 while (n < ino[0]) {
303 if (ino[2] < REAL_KEY && ino[2] != OVFLPAGE) {
304 if (__big_split(hashp, old_bufp,
305 new_bufp, bufp, bufp->addr, obucket, &ret))
306 return (-1);
307 old_bufp = ret.oldp;
308 if (!old_bufp)
309 return (-1);
310 op = (u_int16_t *)old_bufp->page;
311 new_bufp = ret.newp;
312 if (!new_bufp)
313 return (-1);
314 np = (u_int16_t *)new_bufp->page;
315 bufp = ret.nextp;
316 if (!bufp)
317 return (0);
318 cino = (char *)bufp->page;
319 ino = (u_int16_t *)cino;
320 last_bfp = ret.nextp;
321 } else if (ino[n + 1] == OVFLPAGE) {
322 ov_addr = ino[n];
323 /*
324 * Fix up the old page -- the extra 2 are the fields
325 * which contained the overflow information.
326 */
327 ino[0] -= (moved + 2);
328 FREESPACE(ino) =
329 scopyto - sizeof(u_int16_t) * (ino[0] + 3);
330 OFFSET(ino) = scopyto;
331
332 bufp = __get_buf(hashp, ov_addr, bufp, 0);
333 if (!bufp)
334 return (-1);
335
336 ino = (u_int16_t *)bufp->page;
337 n = 1;
338 scopyto = hashp->BSIZE;
339 moved = 0;
340
341 if (last_bfp)
342 __free_ovflpage(hashp, last_bfp);
343 last_bfp = bufp;
344 }
345 /* Move regular sized pairs of there are any */
346 off = hashp->BSIZE;
347 for (n = 1; (n < ino[0]) && (ino[n + 1] >= REAL_KEY); n += 2) {
348 cino = (char *)ino;
349 key.data = (u_char *)cino + ino[n];
350 key.size = off - ino[n];
351 val.data = (u_char *)cino + ino[n + 1];
352 val.size = ino[n] - ino[n + 1];
353 off = ino[n + 1];
354
355 if (__call_hash(hashp, key.data, key.size) == obucket) {
356 /* Keep on old page */
357 if (PAIRFITS(op, (&key), (&val)))
358 putpair((char *)op, &key, &val);
359 else {
360 old_bufp =
361 __add_ovflpage(hashp, old_bufp);
362 if (!old_bufp)
363 return (-1);
364 op = (u_int16_t *)old_bufp->page;
365 putpair((char *)op, &key, &val);
366 }
367 old_bufp->flags |= BUF_MOD;
368 } else {
369 /* Move to new page */
370 if (PAIRFITS(np, (&key), (&val)))
371 putpair((char *)np, &key, &val);
372 else {
373 new_bufp =
374 __add_ovflpage(hashp, new_bufp);
375 if (!new_bufp)
376 return (-1);
377 np = (u_int16_t *)new_bufp->page;
378 putpair((char *)np, &key, &val);
379 }
380 new_bufp->flags |= BUF_MOD;
381 }
382 }
383 }
384 if (last_bfp)
385 __free_ovflpage(hashp, last_bfp);
386 return (0);
387 }
388
389 /*
390 * Add the given pair to the page
391 *
392 * Returns:
393 * 0 ==> OK
394 * 1 ==> failure
395 */
396 int
397 __addel(HTAB *hashp, BUFHEAD *bufp, const DBT *key, const DBT *val)
398 {
399 u_int16_t *bp, *sop;
400 int do_expand;
401
402 bp = (u_int16_t *)bufp->page;
403 do_expand = 0;
404 while (bp[0] && (bp[2] < REAL_KEY || bp[bp[0]] < REAL_KEY))
405 /* Exception case */
406 if (bp[2] == FULL_KEY_DATA && bp[0] == 2)
407 /* This is the last page of a big key/data pair
408 and we need to add another page */
409 break;
410 else if (bp[2] < REAL_KEY && bp[bp[0]] != OVFLPAGE) {
411 bufp = __get_buf(hashp, bp[bp[0] - 1], bufp, 0);
412 if (!bufp)
413 return (-1);
414 bp = (u_int16_t *)bufp->page;
415 } else if (bp[bp[0]] != OVFLPAGE) {
416 /* Short key/data pairs, no more pages */
417 break;
418 } else {
419 /* Try to squeeze key on this page */
420 if (bp[2] >= REAL_KEY &&
421 FREESPACE(bp) >= PAIRSIZE(key, val)) {
422 squeeze_key(bp, key, val);
423 goto stats;
424 } else {
425 bufp = __get_buf(hashp, bp[bp[0] - 1], bufp, 0);
426 if (!bufp)
427 return (-1);
428 bp = (u_int16_t *)bufp->page;
429 }
430 }
431
432 if (PAIRFITS(bp, key, val))
433 putpair(bufp->page, key, val);
434 else {
435 do_expand = 1;
436 bufp = __add_ovflpage(hashp, bufp);
437 if (!bufp)
438 return (-1);
439 sop = (u_int16_t *)bufp->page;
440
441 if (PAIRFITS(sop, key, val))
442 putpair((char *)sop, key, val);
443 else
444 if (__big_insert(hashp, bufp, key, val))
445 return (-1);
446 }
447 stats:
448 bufp->flags |= BUF_MOD;
449 /*
450 * If the average number of keys per bucket exceeds the fill factor,
451 * expand the table.
452 */
453 hashp->NKEYS++;
454 if (do_expand ||
455 (hashp->NKEYS / (hashp->MAX_BUCKET + 1) > hashp->FFACTOR))
456 return (__expand_table(hashp));
457 return (0);
458 }
459
460 /*
461 *
462 * Returns:
463 * pointer on success
464 * NULL on error
465 */
466 BUFHEAD *
467 __add_ovflpage(HTAB *hashp, BUFHEAD *bufp)
468 {
469 u_int16_t *sp, ndx, ovfl_num;
470 #ifdef DEBUG1
471 int tmp1, tmp2;
472 #endif
473 sp = (u_int16_t *)bufp->page;
474
475 /* Check if we are dynamically determining the fill factor */
476 if (hashp->FFACTOR == DEF_FFACTOR) {
477 hashp->FFACTOR = sp[0] >> 1;
478 if (hashp->FFACTOR < MIN_FFACTOR)
479 hashp->FFACTOR = MIN_FFACTOR;
480 }
481 bufp->flags |= BUF_MOD;
482 ovfl_num = overflow_page(hashp);
483 #ifdef DEBUG1
484 tmp1 = bufp->addr;
485 tmp2 = bufp->ovfl ? bufp->ovfl->addr : 0;
486 #endif
487 if (!ovfl_num || !(bufp->ovfl = __get_buf(hashp, ovfl_num, bufp, 1)))
488 return (NULL);
489 bufp->ovfl->flags |= BUF_MOD;
490 #ifdef DEBUG1
491 (void)fprintf(stderr, "ADDOVFLPAGE: %d->ovfl was %d is now %d\n",
492 tmp1, tmp2, bufp->ovfl->addr);
493 #endif
494 ndx = sp[0];
495 /*
496 * Since a pair is allocated on a page only if there's room to add
497 * an overflow page, we know that the OVFL information will fit on
498 * the page.
499 */
500 sp[ndx + 4] = OFFSET(sp);
501 sp[ndx + 3] = FREESPACE(sp) - OVFLSIZE;
502 sp[ndx + 1] = ovfl_num;
503 sp[ndx + 2] = OVFLPAGE;
504 sp[0] = ndx + 2;
505 #ifdef HASH_STATISTICS
506 hash_overflows++;
507 #endif
508 return (bufp->ovfl);
509 }
510
511 /*
512 * Returns:
513 * 0 indicates SUCCESS
514 * -1 indicates FAILURE
515 */
516 int
517 __get_page(HTAB *hashp, char *p, u_int32_t bucket, int is_bucket, int is_disk,
518 int is_bitmap)
519 {
520 int fd, page, size, rsize;
521 u_int16_t *bp;
522
523 fd = hashp->fp;
524 size = hashp->BSIZE;
525
526 if ((fd == -1) || !is_disk) {
527 PAGE_INIT(p);
528 return (0);
529 }
530 if (is_bucket)
531 page = BUCKET_TO_PAGE(bucket);
532 else
533 page = OADDR_TO_PAGE(bucket);
534 if ((rsize = pread(fd, p, size, (off_t)page << hashp->BSHIFT)) == -1)
535 return (-1);
536 bp = (u_int16_t *)p;
537 if (!rsize)
538 bp[0] = 0; /* We hit the EOF, so initialize a new page */
539 else
540 if (rsize != size) {
541 errno = EFTYPE;
542 return (-1);
543 }
544 if (!is_bitmap && !bp[0]) {
545 PAGE_INIT(p);
546 } else
547 if (hashp->LORDER != BYTE_ORDER) {
548 int i, max;
549
550 if (is_bitmap) {
551 max = hashp->BSIZE >> 2; /* divide by 4 */
552 for (i = 0; i < max; i++)
553 M_32_SWAP(((int *)p)[i]);
554 } else {
555 M_16_SWAP(bp[0]);
556 max = bp[0] + 2;
557 for (i = 1; i <= max; i++)
558 M_16_SWAP(bp[i]);
559 }
560 }
561 return (0);
562 }
563
564 /*
565 * Write page p to disk
566 *
567 * Returns:
568 * 0 ==> OK
569 * -1 ==>failure
570 */
571 int
572 __put_page(HTAB *hashp, char *p, u_int32_t bucket, int is_bucket, int is_bitmap)
573 {
574 int fd, page, size, wsize, max;
575
576 size = hashp->BSIZE;
577 if ((hashp->fp == -1) && open_temp(hashp))
578 return (-1);
579 fd = hashp->fp;
580
581 if (hashp->LORDER != BYTE_ORDER) {
582 int i;
583
584 if (is_bitmap) {
585 max = hashp->BSIZE >> 2; /* divide by 4 */
586 for (i = 0; i < max; i++)
587 M_32_SWAP(((int *)p)[i]);
588 } else {
589 max = ((u_int16_t *)p)[0] + 2;
590 for (i = 0; i <= max; i++)
591 M_16_SWAP(((u_int16_t *)p)[i]);
592 }
593 }
594 if (is_bucket)
595 page = BUCKET_TO_PAGE(bucket);
596 else
597 page = OADDR_TO_PAGE(bucket);
598 if ((wsize = pwrite(fd, p, size, (off_t)page << hashp->BSHIFT)) == -1)
599 /* Errno is set */
600 return (-1);
601 if (wsize != size) {
602 errno = EFTYPE;
603 return (-1);
604 }
605 /* 4485533 - reswap the in-memory copy */
606 if (hashp->LORDER != BYTE_ORDER) {
607 int i;
608
609 if (is_bitmap) {
610 for (i = 0; i < max; i++)
611 M_32_SWAP(((int *)p)[i]);
612 } else {
613 for (i = 0; i <= max; i++)
614 M_16_SWAP(((u_int16_t *)p)[i]);
615 }
616 }
617 return (0);
618 }
619
620 #define BYTE_MASK ((1 << INT_BYTE_SHIFT) -1)
621 /*
622 * Initialize a new bitmap page. Bitmap pages are left in memory
623 * once they are read in.
624 */
625 int
626 __ibitmap(HTAB *hashp, int pnum, int nbits, int ndx)
627 {
628 u_int32_t *ip;
629 int clearbytes, clearints;
630
631 if ((ip = (u_int32_t *)malloc(hashp->BSIZE)) == NULL)
632 return (1);
633 hashp->nmaps++;
634 clearints = ((nbits - 1) >> INT_BYTE_SHIFT) + 1;
635 clearbytes = clearints << INT_TO_BYTE;
636 (void)memset((char *)ip, 0, clearbytes);
637 (void)memset(((char *)ip) + clearbytes, 0xFF,
638 hashp->BSIZE - clearbytes);
639 ip[clearints - 1] = ALL_SET << (nbits & BYTE_MASK);
640 SETBIT(ip, 0);
641 hashp->BITMAPS[ndx] = (u_int16_t)pnum;
642 hashp->mapp[ndx] = ip;
643 return (0);
644 }
645
646 static u_int32_t
647 first_free(u_int32_t map)
648 {
649 u_int32_t i, mask;
650
651 mask = 0x1;
652 for (i = 0; i < BITS_PER_MAP; i++) {
653 if (!(mask & map))
654 return (i);
655 mask = mask << 1;
656 }
657 return (i);
658 }
659
660 static u_int16_t
661 overflow_page(HTAB *hashp)
662 {
663 u_int32_t *freep;
664 int max_free, offset, splitnum;
665 u_int16_t addr;
666 int bit, first_page, free_bit, free_page, i, in_use_bits, j;
667 #ifdef DEBUG2
668 int tmp1, tmp2;
669 #endif
670 splitnum = hashp->OVFL_POINT;
671 max_free = hashp->SPARES[splitnum];
672
673 free_page = (max_free - 1) >> (hashp->BSHIFT + BYTE_SHIFT);
674 free_bit = (max_free - 1) & ((hashp->BSIZE << BYTE_SHIFT) - 1);
675
676 /* Look through all the free maps to find the first free block */
677 first_page = hashp->LAST_FREED >>(hashp->BSHIFT + BYTE_SHIFT);
678 for ( i = first_page; i <= free_page; i++ ) {
679 if (!(freep = (u_int32_t *)hashp->mapp[i]) &&
680 !(freep = fetch_bitmap(hashp, i)))
681 return (0);
682 if (i == free_page)
683 in_use_bits = free_bit;
684 else
685 in_use_bits = (hashp->BSIZE << BYTE_SHIFT) - 1;
686
687 if (i == first_page) {
688 bit = hashp->LAST_FREED &
689 ((hashp->BSIZE << BYTE_SHIFT) - 1);
690 j = bit / BITS_PER_MAP;
691 bit = bit & ~(BITS_PER_MAP - 1);
692 } else {
693 bit = 0;
694 j = 0;
695 }
696 for (; bit <= in_use_bits; j++, bit += BITS_PER_MAP)
697 if (freep[j] != ALL_SET)
698 goto found;
699 }
700
701 /* No Free Page Found */
702 hashp->LAST_FREED = hashp->SPARES[splitnum];
703 hashp->SPARES[splitnum]++;
704 offset = hashp->SPARES[splitnum] -
705 (splitnum ? hashp->SPARES[splitnum - 1] : 0);
706
707 #define OVMSG "HASH: Out of overflow pages. Increase page size\n"
708 if (offset > SPLITMASK) {
709 if (++splitnum >= NCACHED) {
710 (void)_write(STDERR_FILENO, OVMSG, sizeof(OVMSG) - 1);
711 errno = EFBIG;
712 return (0);
713 }
714 hashp->OVFL_POINT = splitnum;
715 hashp->SPARES[splitnum] = hashp->SPARES[splitnum-1];
716 hashp->SPARES[splitnum-1]--;
717 offset = 1;
718 }
719
720 /* Check if we need to allocate a new bitmap page */
721 if (free_bit == (hashp->BSIZE << BYTE_SHIFT) - 1) {
722 free_page++;
723 if (free_page >= NCACHED) {
724 (void)_write(STDERR_FILENO, OVMSG, sizeof(OVMSG) - 1);
725 errno = EFBIG;
726 return (0);
727 }
728 /*
729 * This is tricky. The 1 indicates that you want the new page
730 * allocated with 1 clear bit. Actually, you are going to
731 * allocate 2 pages from this map. The first is going to be
732 * the map page, the second is the overflow page we were
733 * looking for. The init_bitmap routine automatically, sets
734 * the first bit of itself to indicate that the bitmap itself
735 * is in use. We would explicitly set the second bit, but
736 * don't have to if we tell init_bitmap not to leave it clear
737 * in the first place.
738 */
739 if (__ibitmap(hashp,
740 (int)OADDR_OF(splitnum, offset), 1, free_page))
741 return (0);
742 hashp->SPARES[splitnum]++;
743 #ifdef DEBUG2
744 free_bit = 2;
745 #endif
746 offset++;
747 if (offset > SPLITMASK) {
748 if (++splitnum >= NCACHED) {
749 (void)_write(STDERR_FILENO, OVMSG,
750 sizeof(OVMSG) - 1);
751 errno = EFBIG;
752 return (0);
753 }
754 hashp->OVFL_POINT = splitnum;
755 hashp->SPARES[splitnum] = hashp->SPARES[splitnum-1];
756 hashp->SPARES[splitnum-1]--;
757 offset = 0;
758 }
759 } else {
760 /*
761 * Free_bit addresses the last used bit. Bump it to address
762 * the first available bit.
763 */
764 free_bit++;
765 SETBIT(freep, free_bit);
766 }
767
768 /* Calculate address of the new overflow page */
769 addr = OADDR_OF(splitnum, offset);
770 #ifdef DEBUG2
771 (void)fprintf(stderr, "OVERFLOW_PAGE: ADDR: %d BIT: %d PAGE %d\n",
772 addr, free_bit, free_page);
773 #endif
774 return (addr);
775
776 found:
777 bit = bit + first_free(freep[j]);
778 SETBIT(freep, bit);
779 #ifdef DEBUG2
780 tmp1 = bit;
781 tmp2 = i;
782 #endif
783 /*
784 * Bits are addressed starting with 0, but overflow pages are addressed
785 * beginning at 1. Bit is a bit addressnumber, so we need to increment
786 * it to convert it to a page number.
787 */
788 bit = 1 + bit + (i * (hashp->BSIZE << BYTE_SHIFT));
789 if (bit >= hashp->LAST_FREED)
790 hashp->LAST_FREED = bit - 1;
791
792 /* Calculate the split number for this page */
793 for (i = 0; (i < splitnum) && (bit > hashp->SPARES[i]); i++);
794 offset = (i ? bit - hashp->SPARES[i - 1] : bit);
795 if (offset >= SPLITMASK) {
796 (void)_write(STDERR_FILENO, OVMSG, sizeof(OVMSG) - 1);
797 errno = EFBIG;
798 return (0); /* Out of overflow pages */
799 }
800 addr = OADDR_OF(i, offset);
801 #ifdef DEBUG2
802 (void)fprintf(stderr, "OVERFLOW_PAGE: ADDR: %d BIT: %d PAGE %d\n",
803 addr, tmp1, tmp2);
804 #endif
805
806 /* Allocate and return the overflow page */
807 return (addr);
808 }
809
810 /*
811 * Mark this overflow page as free.
812 */
813 void
814 __free_ovflpage(HTAB *hashp, BUFHEAD *obufp)
815 {
816 u_int16_t addr;
817 u_int32_t *freep;
818 int bit_address, free_page, free_bit;
819 u_int16_t ndx;
820
821 addr = obufp->addr;
822 #ifdef DEBUG1
823 (void)fprintf(stderr, "Freeing %d\n", addr);
824 #endif
825 ndx = (((u_int16_t)addr) >> SPLITSHIFT);
826 bit_address =
827 (ndx ? hashp->SPARES[ndx - 1] : 0) + (addr & SPLITMASK) - 1;
828 if (bit_address < hashp->LAST_FREED)
829 hashp->LAST_FREED = bit_address;
830 free_page = (bit_address >> (hashp->BSHIFT + BYTE_SHIFT));
831 free_bit = bit_address & ((hashp->BSIZE << BYTE_SHIFT) - 1);
832
833 if (!(freep = hashp->mapp[free_page]))
834 freep = fetch_bitmap(hashp, free_page);
835 #ifdef DEBUG
836 /*
837 * This had better never happen. It means we tried to read a bitmap
838 * that has already had overflow pages allocated off it, and we
839 * failed to read it from the file.
840 */
841 if (!freep)
842 assert(0);
843 #endif
844 CLRBIT(freep, free_bit);
845 #ifdef DEBUG2
846 (void)fprintf(stderr, "FREE_OVFLPAGE: ADDR: %d BIT: %d PAGE %d\n",
847 obufp->addr, free_bit, free_page);
848 #endif
849 __reclaim_buf(hashp, obufp);
850 }
851
852 /*
853 * Returns:
854 * 0 success
855 * -1 failure
856 */
857 static int
858 open_temp(HTAB *hashp)
859 {
860 sigset_t set, oset;
861 int len;
862 char *envtmp = NULL;
863 char path[MAXPATHLEN];
864
865 if (issetugid() == 0)
866 envtmp = getenv("TMPDIR");
867 len = snprintf(path,
868 sizeof(path), "%s/_hash.XXXXXX", envtmp ? envtmp : "/tmp");
869 if (len < 0 || len >= sizeof(path)) {
870 errno = ENAMETOOLONG;
871 return (-1);
872 }
873
874 /* Block signals; make sure file goes away at process exit. */
875 (void)sigfillset(&set);
876 (void)_sigprocmask(SIG_BLOCK, &set, &oset);
877 if ((hashp->fp = mkstemp(path)) != -1) {
878 (void)unlink(path);
879 (void)_fcntl(hashp->fp, F_SETFD, 1);
880 }
881 (void)_sigprocmask(SIG_SETMASK, &oset, (sigset_t *)NULL);
882 return (hashp->fp != -1 ? 0 : -1);
883 }
884
885 /*
886 * We have to know that the key will fit, but the last entry on the page is
887 * an overflow pair, so we need to shift things.
888 */
889 static void
890 squeeze_key(u_int16_t *sp, const DBT *key, const DBT *val)
891 {
892 char *p;
893 u_int16_t free_space, n, off, pageno;
894
895 p = (char *)sp;
896 n = sp[0];
897 free_space = FREESPACE(sp);
898 off = OFFSET(sp);
899
900 pageno = sp[n - 1];
901 off -= key->size;
902 sp[n - 1] = off;
903 memmove(p + off, key->data, key->size);
904 off -= val->size;
905 sp[n] = off;
906 memmove(p + off, val->data, val->size);
907 sp[0] = n + 2;
908 sp[n + 1] = pageno;
909 sp[n + 2] = OVFLPAGE;
910 FREESPACE(sp) = free_space - PAIRSIZE(key, val);
911 OFFSET(sp) = off;
912 }
913
914 static u_int32_t *
915 fetch_bitmap(HTAB *hashp, int ndx)
916 {
917 if (ndx >= hashp->nmaps)
918 return (NULL);
919 if ((hashp->mapp[ndx] = (u_int32_t *)malloc(hashp->BSIZE)) == NULL)
920 return (NULL);
921 if (__get_page(hashp,
922 (char *)hashp->mapp[ndx], hashp->BITMAPS[ndx], 0, 1, 1)) {
923 free(hashp->mapp[ndx]);
924 return (NULL);
925 }
926 return (hashp->mapp[ndx]);
927 }
928
929 #ifdef DEBUG4
930 int
931 print_chain(int addr)
932 {
933 BUFHEAD *bufp;
934 short *bp, oaddr;
935
936 (void)fprintf(stderr, "%d ", addr);
937 bufp = __get_buf(hashp, addr, NULL, 0);
938 bp = (short *)bufp->page;
939 while (bp[0] && ((bp[bp[0]] == OVFLPAGE) ||
940 ((bp[0] > 2) && bp[2] < REAL_KEY))) {
941 oaddr = bp[bp[0] - 1];
942 (void)fprintf(stderr, "%d ", (int)oaddr);
943 bufp = __get_buf(hashp, (int)oaddr, bufp, 0);
944 bp = (short *)bufp->page;
945 }
946 (void)fprintf(stderr, "\n");
947 }
948 #endif