1 /* $OpenBSD: hash_page.c,v 1.23 2016/12/18 17:07:58 krw Exp $ */
2
3 /*-
4 * Copyright (c) 1990, 1993, 1994
5 * The Regents of the University of California. All rights reserved.
6 *
7 * This code is derived from software contributed to Berkeley by
8 * Margo Seltzer.
9 *
10 * Redistribution and use in source and binary forms, with or without
11 * modification, are permitted provided that the following conditions
12 * are met:
13 * 1. Redistributions of source code must retain the above copyright
14 * notice, this list of conditions and the following disclaimer.
15 * 2. Redistributions in binary form must reproduce the above copyright
16 * notice, this list of conditions and the following disclaimer in the
17 * documentation and/or other materials provided with the distribution.
18 * 3. Neither the name of the University nor the names of its contributors
19 * may be used to endorse or promote products derived from this software
20 * without specific prior written permission.
21 *
22 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
23 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
24 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
25 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
26 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
27 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
28 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
29 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
30 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
31 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
32 * SUCH DAMAGE.
33 */
34
35 /*
36 * PACKAGE: hashing
37 *
38 * DESCRIPTION:
39 * Page manipulation for hashing package.
40 *
41 * ROUTINES:
42 *
43 * External
44 * __get_page
45 * __add_ovflpage
46 * Internal
47 * overflow_page
48 * open_temp
49 */
50
51 #include <errno.h>
52 #include <fcntl.h>
53 #include <limits.h>
54 #include <signal.h>
55 #include <stdio.h>
56 #include <stdlib.h>
57 #include <string.h>
58 #include <unistd.h>
59 #ifdef DEBUG
60 #include <assert.h>
61 #endif
62
63 #include <db.h>
64 #include "hash.h"
65 #include "page.h"
66 #include "extern.h"
67
68 static u_int32_t *fetch_bitmap(HTAB *, int);
69 static u_int32_t first_free(u_int32_t);
70 static int open_temp(HTAB *);
71 static u_int16_t overflow_page(HTAB *);
72 static void putpair(char *, const DBT *, const DBT *);
73 static void squeeze_key(u_int16_t *, const DBT *, const DBT *);
74 static int ugly_split(HTAB *, u_int32_t, BUFHEAD *, BUFHEAD *, int, int);
75
76 #define PAGE_INIT(P) { \
77 ((u_int16_t *)(P))[0] = 0; \
78 ((u_int16_t *)(P))[1] = hashp->BSIZE - 3 * sizeof(u_int16_t); \
79 ((u_int16_t *)(P))[2] = hashp->BSIZE; \
80 }
81
82 /*
83 * This is called AFTER we have verified that there is room on the page for
84 * the pair (PAIRFITS has returned true) so we go right ahead and start moving
85 * stuff on.
86 */
87 static void
putpair(char * p,const DBT * key,const DBT * val)88 putpair(char *p, const DBT *key, const DBT *val)
89 {
90 u_int16_t *bp, n, off;
91
92 bp = (u_int16_t *)p;
93
94 /* Enter the key first. */
95 n = bp[0];
96
97 off = OFFSET(bp) - key->size;
98 memmove(p + off, key->data, key->size);
99 bp[++n] = off;
100
101 /* Now the data. */
102 off -= val->size;
103 memmove(p + off, val->data, val->size);
104 bp[++n] = off;
105
106 /* Adjust page info. */
107 bp[0] = n;
108 bp[n + 1] = off - ((n + 3) * sizeof(u_int16_t));
109 bp[n + 2] = off;
110 }
111
112 /*
113 * Returns:
114 * 0 OK
115 * -1 error
116 */
117 int
__delpair(HTAB * hashp,BUFHEAD * bufp,int ndx)118 __delpair(HTAB *hashp, BUFHEAD *bufp, int ndx)
119 {
120 u_int16_t *bp, newoff, pairlen;
121 int n;
122
123 bp = (u_int16_t *)bufp->page;
124 n = bp[0];
125
126 if (bp[ndx + 1] < REAL_KEY)
127 return (__big_delete(hashp, bufp));
128 if (ndx != 1)
129 newoff = bp[ndx - 1];
130 else
131 newoff = hashp->BSIZE;
132 pairlen = newoff - bp[ndx + 1];
133
134 if (ndx != (n - 1)) {
135 /* Hard Case -- need to shuffle keys */
136 int i;
137 char *src = bufp->page + (int)OFFSET(bp);
138 char *dst = src + (int)pairlen;
139 memmove(dst, src, bp[ndx + 1] - OFFSET(bp));
140
141 /* Now adjust the pointers */
142 for (i = ndx + 2; i <= n; i += 2) {
143 if (bp[i + 1] == OVFLPAGE) {
144 bp[i - 2] = bp[i];
145 bp[i - 1] = bp[i + 1];
146 } else {
147 bp[i - 2] = bp[i] + pairlen;
148 bp[i - 1] = bp[i + 1] + pairlen;
149 }
150 }
151 if (ndx == hashp->cndx) {
152 /*
153 * We just removed pair we were "pointing" to.
154 * By moving back the cndx we ensure subsequent
155 * hash_seq() calls won't skip over any entries.
156 */
157 hashp->cndx -= 2;
158 }
159 }
160 /* Finally adjust the page data */
161 bp[n] = OFFSET(bp) + pairlen;
162 bp[n - 1] = bp[n + 1] + pairlen + 2 * sizeof(u_int16_t);
163 bp[0] = n - 2;
164 hashp->NKEYS--;
165
166 bufp->flags |= BUF_MOD;
167 return (0);
168 }
169 /*
170 * Returns:
171 * 0 ==> OK
172 * -1 ==> Error
173 */
174 int
__split_page(HTAB * hashp,u_int32_t obucket,u_int32_t nbucket)175 __split_page(HTAB *hashp, u_int32_t obucket, u_int32_t nbucket)
176 {
177 BUFHEAD *new_bufp, *old_bufp;
178 u_int16_t *ino;
179 char *np;
180 DBT key, val;
181 int n, ndx, retval;
182 u_int16_t copyto, diff, off, moved;
183 char *op;
184
185 copyto = (u_int16_t)hashp->BSIZE;
186 off = (u_int16_t)hashp->BSIZE;
187 old_bufp = __get_buf(hashp, obucket, NULL, 0);
188 if (old_bufp == NULL)
189 return (-1);
190 new_bufp = __get_buf(hashp, nbucket, NULL, 0);
191 if (new_bufp == NULL)
192 return (-1);
193
194 old_bufp->flags |= (BUF_MOD | BUF_PIN);
195 new_bufp->flags |= (BUF_MOD | BUF_PIN);
196
197 ino = (u_int16_t *)(op = old_bufp->page);
198 np = new_bufp->page;
199
200 moved = 0;
201
202 for (n = 1, ndx = 1; n < ino[0]; n += 2) {
203 if (ino[n + 1] < REAL_KEY) {
204 retval = ugly_split(hashp, obucket, old_bufp, new_bufp,
205 (int)copyto, (int)moved);
206 old_bufp->flags &= ~BUF_PIN;
207 new_bufp->flags &= ~BUF_PIN;
208 return (retval);
209
210 }
211 key.data = (u_char *)op + ino[n];
212 key.size = off - ino[n];
213
214 if (__call_hash(hashp, key.data, key.size) == obucket) {
215 /* Don't switch page */
216 diff = copyto - off;
217 if (diff) {
218 copyto = ino[n + 1] + diff;
219 memmove(op + copyto, op + ino[n + 1],
220 off - ino[n + 1]);
221 ino[ndx] = copyto + ino[n] - ino[n + 1];
222 ino[ndx + 1] = copyto;
223 } else
224 copyto = ino[n + 1];
225 ndx += 2;
226 } else {
227 /* Switch page */
228 val.data = (u_char *)op + ino[n + 1];
229 val.size = ino[n] - ino[n + 1];
230 putpair(np, &key, &val);
231 moved += 2;
232 }
233
234 off = ino[n + 1];
235 }
236
237 /* Now clean up the page */
238 ino[0] -= moved;
239 FREESPACE(ino) = copyto - sizeof(u_int16_t) * (ino[0] + 3);
240 OFFSET(ino) = copyto;
241
242 #ifdef DEBUG3
243 (void)fprintf(stderr, "split %d/%d\n",
244 ((u_int16_t *)np)[0] / 2,
245 ((u_int16_t *)op)[0] / 2);
246 #endif
247 /* unpin both pages */
248 old_bufp->flags &= ~BUF_PIN;
249 new_bufp->flags &= ~BUF_PIN;
250 return (0);
251 }
252
253 /*
254 * Called when we encounter an overflow or big key/data page during split
255 * handling. This is special cased since we have to begin checking whether
256 * the key/data pairs fit on their respective pages and because we may need
257 * overflow pages for both the old and new pages.
258 *
259 * The first page might be a page with regular key/data pairs in which case
260 * we have a regular overflow condition and just need to go on to the next
261 * page or it might be a big key/data pair in which case we need to fix the
262 * big key/data pair.
263 *
264 * Returns:
265 * 0 ==> success
266 * -1 ==> failure
267 */
268 static int
ugly_split(HTAB * hashp,u_int32_t obucket,BUFHEAD * old_bufp,BUFHEAD * new_bufp,int copyto,int moved)269 ugly_split(HTAB *hashp,
270 u_int32_t obucket, /* Same as __split_page. */
271 BUFHEAD *old_bufp,
272 BUFHEAD *new_bufp,
273 int copyto, /* First byte on page which contains key/data values. */
274 int moved) /* Number of pairs moved to new page. */
275 {
276 BUFHEAD *bufp; /* Buffer header for ino */
277 u_int16_t *ino; /* Page keys come off of */
278 u_int16_t *np; /* New page */
279 u_int16_t *op; /* Page keys go on to if they aren't moving */
280
281 BUFHEAD *last_bfp; /* Last buf header OVFL needing to be freed */
282 DBT key, val;
283 SPLIT_RETURN ret;
284 u_int16_t n, off, ov_addr, scopyto;
285 char *cino; /* Character value of ino */
286
287 bufp = old_bufp;
288 ino = (u_int16_t *)old_bufp->page;
289 np = (u_int16_t *)new_bufp->page;
290 op = (u_int16_t *)old_bufp->page;
291 last_bfp = NULL;
292 scopyto = (u_int16_t)copyto; /* ANSI */
293
294 n = ino[0] - 1;
295 while (n < ino[0]) {
296 if (ino[2] < REAL_KEY && ino[2] != OVFLPAGE) {
297 if (__big_split(hashp, old_bufp,
298 new_bufp, bufp, bufp->addr, obucket, &ret))
299 return (-1);
300 old_bufp = ret.oldp;
301 if (!old_bufp)
302 return (-1);
303 op = (u_int16_t *)old_bufp->page;
304 new_bufp = ret.newp;
305 if (!new_bufp)
306 return (-1);
307 np = (u_int16_t *)new_bufp->page;
308 bufp = ret.nextp;
309 if (!bufp)
310 return (0);
311 cino = (char *)bufp->page;
312 ino = (u_int16_t *)cino;
313 last_bfp = ret.nextp;
314 } else if (ino[n + 1] == OVFLPAGE) {
315 ov_addr = ino[n];
316 /*
317 * Fix up the old page -- the extra 2 are the fields
318 * which contained the overflow information.
319 */
320 ino[0] -= (moved + 2);
321 FREESPACE(ino) =
322 scopyto - sizeof(u_int16_t) * (ino[0] + 3);
323 OFFSET(ino) = scopyto;
324
325 bufp = __get_buf(hashp, ov_addr, bufp, 0);
326 if (!bufp)
327 return (-1);
328
329 ino = (u_int16_t *)bufp->page;
330 n = 1;
331 scopyto = hashp->BSIZE;
332 moved = 0;
333
334 if (last_bfp)
335 __free_ovflpage(hashp, last_bfp);
336 last_bfp = bufp;
337 }
338 /* Move regular sized pairs of there are any */
339 off = hashp->BSIZE;
340 for (n = 1; (n < ino[0]) && (ino[n + 1] >= REAL_KEY); n += 2) {
341 cino = (char *)ino;
342 key.data = (u_char *)cino + ino[n];
343 key.size = off - ino[n];
344 val.data = (u_char *)cino + ino[n + 1];
345 val.size = ino[n] - ino[n + 1];
346 off = ino[n + 1];
347
348 if (__call_hash(hashp, key.data, key.size) == obucket) {
349 /* Keep on old page */
350 if (PAIRFITS(op, (&key), (&val)))
351 putpair((char *)op, &key, &val);
352 else {
353 old_bufp =
354 __add_ovflpage(hashp, old_bufp);
355 if (!old_bufp)
356 return (-1);
357 op = (u_int16_t *)old_bufp->page;
358 putpair((char *)op, &key, &val);
359 }
360 old_bufp->flags |= BUF_MOD;
361 } else {
362 /* Move to new page */
363 if (PAIRFITS(np, (&key), (&val)))
364 putpair((char *)np, &key, &val);
365 else {
366 new_bufp =
367 __add_ovflpage(hashp, new_bufp);
368 if (!new_bufp)
369 return (-1);
370 np = (u_int16_t *)new_bufp->page;
371 putpair((char *)np, &key, &val);
372 }
373 new_bufp->flags |= BUF_MOD;
374 }
375 }
376 }
377 if (last_bfp)
378 __free_ovflpage(hashp, last_bfp);
379 return (0);
380 }
381
382 /*
383 * Add the given pair to the page
384 *
385 * Returns:
386 * 0 ==> OK
387 * 1 ==> failure
388 */
389 int
__addel(HTAB * hashp,BUFHEAD * bufp,const DBT * key,const DBT * val)390 __addel(HTAB *hashp, BUFHEAD *bufp, const DBT *key, const DBT *val)
391 {
392 u_int16_t *bp, *sop;
393 int do_expand;
394
395 bp = (u_int16_t *)bufp->page;
396 do_expand = 0;
397 while (bp[0] && (bp[2] < REAL_KEY || bp[bp[0]] < REAL_KEY))
398 /* Exception case */
399 if (bp[2] == FULL_KEY_DATA && bp[0] == 2)
400 /* This is the last page of a big key/data pair
401 and we need to add another page */
402 break;
403 else if (bp[2] < REAL_KEY && bp[bp[0]] != OVFLPAGE) {
404 bufp = __get_buf(hashp, bp[bp[0] - 1], bufp, 0);
405 if (!bufp)
406 return (-1);
407 bp = (u_int16_t *)bufp->page;
408 } else if (bp[bp[0]] != OVFLPAGE) {
409 /* Short key/data pairs, no more pages */
410 break;
411 } else {
412 /* Try to squeeze key on this page */
413 if (bp[2] >= REAL_KEY &&
414 FREESPACE(bp) >= PAIRSIZE(key, val)) {
415 squeeze_key(bp, key, val);
416 goto stats;
417 } else {
418 bufp = __get_buf(hashp, bp[bp[0] - 1], bufp, 0);
419 if (!bufp)
420 return (-1);
421 bp = (u_int16_t *)bufp->page;
422 }
423 }
424
425 if (PAIRFITS(bp, key, val))
426 putpair(bufp->page, key, val);
427 else {
428 do_expand = 1;
429 bufp = __add_ovflpage(hashp, bufp);
430 if (!bufp)
431 return (-1);
432 sop = (u_int16_t *)bufp->page;
433
434 if (PAIRFITS(sop, key, val))
435 putpair((char *)sop, key, val);
436 else
437 if (__big_insert(hashp, bufp, key, val))
438 return (-1);
439 }
440 stats:
441 bufp->flags |= BUF_MOD;
442 /*
443 * If the average number of keys per bucket exceeds the fill factor,
444 * expand the table.
445 */
446 hashp->NKEYS++;
447 if (do_expand ||
448 (hashp->NKEYS / (hashp->MAX_BUCKET + 1) > hashp->FFACTOR))
449 return (__expand_table(hashp));
450 return (0);
451 }
452
453 /*
454 *
455 * Returns:
456 * pointer on success
457 * NULL on error
458 */
459 BUFHEAD *
__add_ovflpage(HTAB * hashp,BUFHEAD * bufp)460 __add_ovflpage(HTAB *hashp, BUFHEAD *bufp)
461 {
462 u_int16_t *sp, ndx, ovfl_num;
463 #ifdef DEBUG1
464 int tmp1, tmp2;
465 #endif
466 sp = (u_int16_t *)bufp->page;
467
468 /* Check if we are dynamically determining the fill factor */
469 if (hashp->FFACTOR == DEF_FFACTOR) {
470 hashp->FFACTOR = sp[0] >> 1;
471 if (hashp->FFACTOR < MIN_FFACTOR)
472 hashp->FFACTOR = MIN_FFACTOR;
473 }
474 bufp->flags |= BUF_MOD;
475 ovfl_num = overflow_page(hashp);
476 #ifdef DEBUG1
477 tmp1 = bufp->addr;
478 tmp2 = bufp->ovfl ? bufp->ovfl->addr : 0;
479 #endif
480 if (!ovfl_num || !(bufp->ovfl = __get_buf(hashp, ovfl_num, bufp, 1)))
481 return (NULL);
482 bufp->ovfl->flags |= BUF_MOD;
483 #ifdef DEBUG1
484 (void)fprintf(stderr, "ADDOVFLPAGE: %d->ovfl was %d is now %d\n",
485 tmp1, tmp2, bufp->ovfl->addr);
486 #endif
487 ndx = sp[0];
488 /*
489 * Since a pair is allocated on a page only if there's room to add
490 * an overflow page, we know that the OVFL information will fit on
491 * the page.
492 */
493 sp[ndx + 4] = OFFSET(sp);
494 sp[ndx + 3] = FREESPACE(sp) - OVFLSIZE;
495 sp[ndx + 1] = ovfl_num;
496 sp[ndx + 2] = OVFLPAGE;
497 sp[0] = ndx + 2;
498 #ifdef HASH_STATISTICS
499 hash_overflows++;
500 #endif
501 return (bufp->ovfl);
502 }
503
504 /*
505 * Returns:
506 * 0 indicates SUCCESS
507 * -1 indicates FAILURE
508 */
509 int
__get_page(HTAB * hashp,char * p,u_int32_t bucket,int is_bucket,int is_disk,int is_bitmap)510 __get_page(HTAB *hashp, char *p, u_int32_t bucket, int is_bucket, int is_disk,
511 int is_bitmap)
512 {
513 int fd, page, size, rsize;
514 u_int16_t *bp;
515
516 fd = hashp->fp;
517 size = hashp->BSIZE;
518
519 if ((fd == -1) || !is_disk) {
520 PAGE_INIT(p);
521 return (0);
522 }
523 if (is_bucket)
524 page = BUCKET_TO_PAGE(bucket);
525 else
526 page = OADDR_TO_PAGE(bucket);
527 if ((rsize = pread(fd, p, size, (off_t)page << hashp->BSHIFT)) == -1)
528 return (-1);
529 bp = (u_int16_t *)p;
530 if (!rsize)
531 bp[0] = 0; /* We hit the EOF, so initialize a new page */
532 else
533 if (rsize != size) {
534 errno = EFTYPE;
535 return (-1);
536 }
537 if (!is_bitmap && !bp[0]) {
538 PAGE_INIT(p);
539 } else
540 if (hashp->LORDER != BYTE_ORDER) {
541 int i, max;
542
543 if (is_bitmap) {
544 max = hashp->BSIZE >> 2; /* divide by 4 */
545 for (i = 0; i < max; i++)
546 M_32_SWAP(((int *)p)[i]);
547 } else {
548 M_16_SWAP(bp[0]);
549 max = bp[0] + 2;
550 for (i = 1; i <= max; i++)
551 M_16_SWAP(bp[i]);
552 }
553 }
554 return (0);
555 }
556
557 /*
558 * Write page p to disk
559 *
560 * Returns:
561 * 0 ==> OK
562 * -1 ==>failure
563 */
564 int
__put_page(HTAB * hashp,char * p,u_int32_t bucket,int is_bucket,int is_bitmap)565 __put_page(HTAB *hashp, char *p, u_int32_t bucket, int is_bucket, int is_bitmap)
566 {
567 int fd, page, size, wsize;
568
569 size = hashp->BSIZE;
570 if ((hashp->fp == -1) && open_temp(hashp))
571 return (-1);
572 fd = hashp->fp;
573
574 if (hashp->LORDER != BYTE_ORDER) {
575 int i, max;
576
577 if (is_bitmap) {
578 max = hashp->BSIZE >> 2; /* divide by 4 */
579 for (i = 0; i < max; i++)
580 M_32_SWAP(((int *)p)[i]);
581 } else {
582 max = ((u_int16_t *)p)[0] + 2;
583 for (i = 0; i <= max; i++)
584 M_16_SWAP(((u_int16_t *)p)[i]);
585 }
586 }
587 if (is_bucket)
588 page = BUCKET_TO_PAGE(bucket);
589 else
590 page = OADDR_TO_PAGE(bucket);
591 if ((wsize = pwrite(fd, p, size, (off_t)page << hashp->BSHIFT)) == -1)
592 /* Errno is set */
593 return (-1);
594 if (wsize != size) {
595 errno = EFTYPE;
596 return (-1);
597 }
598 return (0);
599 }
600
601 #define BYTE_MASK ((1 << INT_BYTE_SHIFT) -1)
602 /*
603 * Initialize a new bitmap page. Bitmap pages are left in memory
604 * once they are read in.
605 */
606 int
__ibitmap(HTAB * hashp,int pnum,int nbits,int ndx)607 __ibitmap(HTAB *hashp, int pnum, int nbits, int ndx)
608 {
609 u_int32_t *ip;
610 int clearbytes, clearints;
611
612 if ((ip = (u_int32_t *)malloc(hashp->BSIZE)) == NULL)
613 return (1);
614 hashp->nmaps++;
615 clearints = ((nbits - 1) >> INT_BYTE_SHIFT) + 1;
616 clearbytes = clearints << INT_TO_BYTE;
617 (void)memset((char *)ip, 0, clearbytes);
618 (void)memset(((char *)ip) + clearbytes, 0xFF,
619 hashp->BSIZE - clearbytes);
620 ip[clearints - 1] = ALL_SET << (nbits & BYTE_MASK);
621 SETBIT(ip, 0);
622 hashp->BITMAPS[ndx] = (u_int16_t)pnum;
623 hashp->mapp[ndx] = ip;
624 return (0);
625 }
626
627 static u_int32_t
first_free(u_int32_t map)628 first_free(u_int32_t map)
629 {
630 u_int32_t i, mask;
631
632 mask = 0x1;
633 for (i = 0; i < BITS_PER_MAP; i++) {
634 if (!(mask & map))
635 return (i);
636 mask = mask << 1;
637 }
638 return (i);
639 }
640
641 static u_int16_t
overflow_page(HTAB * hashp)642 overflow_page(HTAB *hashp)
643 {
644 u_int32_t *freep;
645 int max_free, offset, splitnum;
646 u_int16_t addr;
647 int bit, first_page, free_bit, free_page, i, in_use_bits, j;
648 #ifdef DEBUG2
649 int tmp1, tmp2;
650 #endif
651 splitnum = hashp->OVFL_POINT;
652 max_free = hashp->SPARES[splitnum];
653
654 free_page = (max_free - 1) >> (hashp->BSHIFT + BYTE_SHIFT);
655 free_bit = (max_free - 1) & ((hashp->BSIZE << BYTE_SHIFT) - 1);
656
657 /* Look through all the free maps to find the first free block */
658 first_page = hashp->LAST_FREED >>(hashp->BSHIFT + BYTE_SHIFT);
659 for ( i = first_page; i <= free_page; i++ ) {
660 if (!(freep = (u_int32_t *)hashp->mapp[i]) &&
661 !(freep = fetch_bitmap(hashp, i)))
662 return (0);
663 if (i == free_page)
664 in_use_bits = free_bit;
665 else
666 in_use_bits = (hashp->BSIZE << BYTE_SHIFT) - 1;
667
668 if (i == first_page) {
669 bit = hashp->LAST_FREED &
670 ((hashp->BSIZE << BYTE_SHIFT) - 1);
671 j = bit / BITS_PER_MAP;
672 bit = bit & ~(BITS_PER_MAP - 1);
673 } else {
674 bit = 0;
675 j = 0;
676 }
677 for (; bit <= in_use_bits; j++, bit += BITS_PER_MAP)
678 if (freep[j] != ALL_SET)
679 goto found;
680 }
681
682 /* No Free Page Found */
683 hashp->LAST_FREED = hashp->SPARES[splitnum];
684 hashp->SPARES[splitnum]++;
685 offset = hashp->SPARES[splitnum] -
686 (splitnum ? hashp->SPARES[splitnum - 1] : 0);
687
688 #define OVMSG "HASH: Out of overflow pages. Increase page size\n"
689 if (offset > SPLITMASK) {
690 if (++splitnum >= NCACHED) {
691 (void)write(STDERR_FILENO, OVMSG, sizeof(OVMSG) - 1);
692 errno = EFBIG;
693 return (0);
694 }
695 hashp->OVFL_POINT = splitnum;
696 hashp->SPARES[splitnum] = hashp->SPARES[splitnum-1];
697 hashp->SPARES[splitnum-1]--;
698 offset = 1;
699 }
700
701 /* Check if we need to allocate a new bitmap page */
702 if (free_bit == (hashp->BSIZE << BYTE_SHIFT) - 1) {
703 free_page++;
704 if (free_page >= NCACHED) {
705 (void)write(STDERR_FILENO, OVMSG, sizeof(OVMSG) - 1);
706 errno = EFBIG;
707 return (0);
708 }
709 /*
710 * This is tricky. The 1 indicates that you want the new page
711 * allocated with 1 clear bit. Actually, you are going to
712 * allocate 2 pages from this map. The first is going to be
713 * the map page, the second is the overflow page we were
714 * looking for. The init_bitmap routine automatically, sets
715 * the first bit of itself to indicate that the bitmap itself
716 * is in use. We would explicitly set the second bit, but
717 * don't have to if we tell init_bitmap not to leave it clear
718 * in the first place.
719 */
720 if (__ibitmap(hashp,
721 (int)OADDR_OF(splitnum, offset), 1, free_page))
722 return (0);
723 hashp->SPARES[splitnum]++;
724 #ifdef DEBUG2
725 free_bit = 2;
726 #endif
727 offset++;
728 if (offset > SPLITMASK) {
729 if (++splitnum >= NCACHED) {
730 (void)write(STDERR_FILENO, OVMSG,
731 sizeof(OVMSG) - 1);
732 errno = EFBIG;
733 return (0);
734 }
735 hashp->OVFL_POINT = splitnum;
736 hashp->SPARES[splitnum] = hashp->SPARES[splitnum-1];
737 hashp->SPARES[splitnum-1]--;
738 offset = 0;
739 }
740 } else {
741 /*
742 * Free_bit addresses the last used bit. Bump it to address
743 * the first available bit.
744 */
745 free_bit++;
746 SETBIT(freep, free_bit);
747 }
748
749 /* Calculate address of the new overflow page */
750 addr = OADDR_OF(splitnum, offset);
751 #ifdef DEBUG2
752 (void)fprintf(stderr, "OVERFLOW_PAGE: ADDR: %d BIT: %d PAGE %d\n",
753 addr, free_bit, free_page);
754 #endif
755 return (addr);
756
757 found:
758 bit = bit + first_free(freep[j]);
759 SETBIT(freep, bit);
760 #ifdef DEBUG2
761 tmp1 = bit;
762 tmp2 = i;
763 #endif
764 /*
765 * Bits are addressed starting with 0, but overflow pages are addressed
766 * beginning at 1. Bit is a bit addressnumber, so we need to increment
767 * it to convert it to a page number.
768 */
769 bit = 1 + bit + (i * (hashp->BSIZE << BYTE_SHIFT));
770 if (bit >= hashp->LAST_FREED)
771 hashp->LAST_FREED = bit - 1;
772
773 /* Calculate the split number for this page */
774 for (i = 0; (i < splitnum) && (bit > hashp->SPARES[i]); i++);
775 offset = (i ? bit - hashp->SPARES[i - 1] : bit);
776 if (offset >= SPLITMASK) {
777 (void)write(STDERR_FILENO, OVMSG, sizeof(OVMSG) - 1);
778 errno = EFBIG;
779 return (0); /* Out of overflow pages */
780 }
781 addr = OADDR_OF(i, offset);
782 #ifdef DEBUG2
783 (void)fprintf(stderr, "OVERFLOW_PAGE: ADDR: %d BIT: %d PAGE %d\n",
784 addr, tmp1, tmp2);
785 #endif
786
787 /* Allocate and return the overflow page */
788 return (addr);
789 }
790
791 /*
792 * Mark this overflow page as free.
793 */
794 void
__free_ovflpage(HTAB * hashp,BUFHEAD * obufp)795 __free_ovflpage(HTAB *hashp, BUFHEAD *obufp)
796 {
797 u_int16_t addr;
798 u_int32_t *freep;
799 int bit_address, free_page, free_bit;
800 u_int16_t ndx;
801
802 addr = obufp->addr;
803 #ifdef DEBUG1
804 (void)fprintf(stderr, "Freeing %d\n", addr);
805 #endif
806 ndx = (((u_int16_t)addr) >> SPLITSHIFT);
807 bit_address =
808 (ndx ? hashp->SPARES[ndx - 1] : 0) + (addr & SPLITMASK) - 1;
809 if (bit_address < hashp->LAST_FREED)
810 hashp->LAST_FREED = bit_address;
811 free_page = (bit_address >> (hashp->BSHIFT + BYTE_SHIFT));
812 free_bit = bit_address & ((hashp->BSIZE << BYTE_SHIFT) - 1);
813
814 if (!(freep = hashp->mapp[free_page]))
815 freep = fetch_bitmap(hashp, free_page);
816 #ifdef DEBUG
817 /*
818 * This had better never happen. It means we tried to read a bitmap
819 * that has already had overflow pages allocated off it, and we
820 * failed to read it from the file.
821 */
822 if (!freep)
823 assert(0);
824 #endif
825 CLRBIT(freep, free_bit);
826 #ifdef DEBUG2
827 (void)fprintf(stderr, "FREE_OVFLPAGE: ADDR: %d BIT: %d PAGE %d\n",
828 obufp->addr, free_bit, free_page);
829 #endif
830 __reclaim_buf(hashp, obufp);
831 }
832
833 /*
834 * Returns:
835 * 0 success
836 * -1 failure
837 */
838 static int
open_temp(HTAB * hashp)839 open_temp(HTAB *hashp)
840 {
841 sigset_t set, oset;
842 int len;
843 char *envtmp = NULL;
844 char path[PATH_MAX];
845
846 if (issetugid() == 0)
847 envtmp = getenv("TMPDIR");
848 len = snprintf(path,
849 sizeof(path), "%s/_hash.XXXXXX", envtmp ? envtmp : "/tmp");
850 if (len < 0 || len >= sizeof(path)) {
851 errno = ENAMETOOLONG;
852 return (-1);
853 }
854
855 /* Block signals; make sure file goes away at process exit. */
856 (void)sigfillset(&set);
857 (void)sigprocmask(SIG_BLOCK, &set, &oset);
858 if ((hashp->fp = mkostemp(path, O_CLOEXEC)) != -1) {
859 (void)unlink(path);
860 }
861 (void)sigprocmask(SIG_SETMASK, &oset, (sigset_t *)NULL);
862 return (hashp->fp != -1 ? 0 : -1);
863 }
864
865 /*
866 * We have to know that the key will fit, but the last entry on the page is
867 * an overflow pair, so we need to shift things.
868 */
869 static void
squeeze_key(u_int16_t * sp,const DBT * key,const DBT * val)870 squeeze_key(u_int16_t *sp, const DBT *key, const DBT *val)
871 {
872 char *p;
873 u_int16_t free_space, n, off, pageno;
874
875 p = (char *)sp;
876 n = sp[0];
877 free_space = FREESPACE(sp);
878 off = OFFSET(sp);
879
880 pageno = sp[n - 1];
881 off -= key->size;
882 sp[n - 1] = off;
883 memmove(p + off, key->data, key->size);
884 off -= val->size;
885 sp[n] = off;
886 memmove(p + off, val->data, val->size);
887 sp[0] = n + 2;
888 sp[n + 1] = pageno;
889 sp[n + 2] = OVFLPAGE;
890 FREESPACE(sp) = free_space - PAIRSIZE(key, val);
891 OFFSET(sp) = off;
892 }
893
894 static u_int32_t *
fetch_bitmap(HTAB * hashp,int ndx)895 fetch_bitmap(HTAB *hashp, int ndx)
896 {
897 if (ndx >= hashp->nmaps)
898 return (NULL);
899 if ((hashp->mapp[ndx] = (u_int32_t *)malloc(hashp->BSIZE)) == NULL)
900 return (NULL);
901 if (__get_page(hashp,
902 (char *)hashp->mapp[ndx], hashp->BITMAPS[ndx], 0, 1, 1)) {
903 free(hashp->mapp[ndx]);
904 return (NULL);
905 }
906 return (hashp->mapp[ndx]);
907 }
908
909 #ifdef DEBUG4
910 int
print_chain(int addr)911 print_chain(int addr)
912 {
913 BUFHEAD *bufp;
914 short *bp, oaddr;
915
916 (void)fprintf(stderr, "%d ", addr);
917 bufp = __get_buf(hashp, addr, NULL, 0);
918 bp = (short *)bufp->page;
919 while (bp[0] && ((bp[bp[0]] == OVFLPAGE) ||
920 ((bp[0] > 2) && bp[2] < REAL_KEY))) {
921 oaddr = bp[bp[0] - 1];
922 (void)fprintf(stderr, "%d ", (int)oaddr);
923 bufp = __get_buf(hashp, (int)oaddr, bufp, 0);
924 bp = (short *)bufp->page;
925 }
926 (void)fprintf(stderr, "\n");
927 }
928 #endif
929