1 /*-
2 * SPDX-License-Identifier: BSD-3-Clause
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 "namespace.h"
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 #include "un-namespace.h"
65 #include "libc_private.h"
66
67 #include <db.h>
68 #include "hash.h"
69 #include "page.h"
70 #include "extern.h"
71
72 static u_int32_t *fetch_bitmap(HTAB *, int);
73 static u_int32_t first_free(u_int32_t);
74 static int open_temp(HTAB *);
75 static u_int16_t overflow_page(HTAB *);
76 static void putpair(char *, const DBT *, const DBT *);
77 static void squeeze_key(u_int16_t *, const DBT *, const DBT *);
78 static int ugly_split(HTAB *, u_int32_t, BUFHEAD *, BUFHEAD *, int, int);
79
80 #define PAGE_INIT(P) { \
81 ((u_int16_t *)(P))[0] = 0; \
82 ((u_int16_t *)(P))[1] = hashp->BSIZE - 3 * sizeof(u_int16_t); \
83 ((u_int16_t *)(P))[2] = hashp->BSIZE; \
84 }
85
86 /*
87 * This is called AFTER we have verified that there is room on the page for
88 * the pair (PAIRFITS has returned true) so we go right ahead and start moving
89 * stuff on.
90 */
91 static void
putpair(char * p,const DBT * key,const DBT * val)92 putpair(char *p, const DBT *key, const DBT *val)
93 {
94 u_int16_t *bp, n, off;
95
96 bp = (u_int16_t *)p;
97
98 /* Enter the key first. */
99 n = bp[0];
100
101 off = OFFSET(bp) - key->size;
102 memmove(p + off, key->data, key->size);
103 bp[++n] = off;
104
105 /* Now the data. */
106 off -= val->size;
107 memmove(p + off, val->data, val->size);
108 bp[++n] = off;
109
110 /* Adjust page info. */
111 bp[0] = n;
112 bp[n + 1] = off - ((n + 3) * sizeof(u_int16_t));
113 bp[n + 2] = off;
114 }
115
116 /*
117 * Returns:
118 * 0 OK
119 * -1 error
120 */
121 int
__delpair(HTAB * hashp,BUFHEAD * bufp,int ndx)122 __delpair(HTAB *hashp, BUFHEAD *bufp, int ndx)
123 {
124 u_int16_t *bp, newoff, pairlen;
125 int n;
126
127 bp = (u_int16_t *)bufp->page;
128 n = bp[0];
129
130 if (bp[ndx + 1] < REAL_KEY)
131 return (__big_delete(hashp, bufp));
132 if (ndx != 1)
133 newoff = bp[ndx - 1];
134 else
135 newoff = hashp->BSIZE;
136 pairlen = newoff - bp[ndx + 1];
137
138 if (ndx != (n - 1)) {
139 /* Hard Case -- need to shuffle keys */
140 int i;
141 char *src = bufp->page + (int)OFFSET(bp);
142 char *dst = src + (int)pairlen;
143 memmove(dst, src, bp[ndx + 1] - OFFSET(bp));
144
145 /* Now adjust the pointers */
146 for (i = ndx + 2; i <= n; i += 2) {
147 if (bp[i + 1] == OVFLPAGE) {
148 bp[i - 2] = bp[i];
149 bp[i - 1] = bp[i + 1];
150 } else {
151 bp[i - 2] = bp[i] + pairlen;
152 bp[i - 1] = bp[i + 1] + pairlen;
153 }
154 }
155 if (ndx == hashp->cndx) {
156 /*
157 * We just removed pair we were "pointing" to.
158 * By moving back the cndx we ensure subsequent
159 * hash_seq() calls won't skip over any entries.
160 */
161 hashp->cndx -= 2;
162 }
163 }
164 /* Finally adjust the page data */
165 bp[n] = OFFSET(bp) + pairlen;
166 bp[n - 1] = bp[n + 1] + pairlen + 2 * sizeof(u_int16_t);
167 bp[0] = n - 2;
168 hashp->NKEYS--;
169
170 bufp->flags |= BUF_MOD;
171 return (0);
172 }
173 /*
174 * Returns:
175 * 0 ==> OK
176 * -1 ==> Error
177 */
178 int
__split_page(HTAB * hashp,u_int32_t obucket,u_int32_t nbucket)179 __split_page(HTAB *hashp, u_int32_t obucket, u_int32_t nbucket)
180 {
181 BUFHEAD *new_bufp, *old_bufp;
182 u_int16_t *ino;
183 char *np;
184 DBT key, val;
185 int n, ndx, retval;
186 u_int16_t copyto, diff, off, moved;
187 char *op;
188
189 copyto = (u_int16_t)hashp->BSIZE;
190 off = (u_int16_t)hashp->BSIZE;
191 old_bufp = __get_buf(hashp, obucket, NULL, 0);
192 if (old_bufp == NULL)
193 return (-1);
194 new_bufp = __get_buf(hashp, nbucket, NULL, 0);
195 if (new_bufp == NULL)
196 return (-1);
197
198 old_bufp->flags |= (BUF_MOD | BUF_PIN);
199 new_bufp->flags |= (BUF_MOD | BUF_PIN);
200
201 ino = (u_int16_t *)(op = old_bufp->page);
202 np = new_bufp->page;
203
204 moved = 0;
205
206 for (n = 1, ndx = 1; n < ino[0]; n += 2) {
207 if (ino[n + 1] < REAL_KEY) {
208 retval = ugly_split(hashp, obucket, old_bufp, new_bufp,
209 (int)copyto, (int)moved);
210 old_bufp->flags &= ~BUF_PIN;
211 new_bufp->flags &= ~BUF_PIN;
212 return (retval);
213
214 }
215 key.data = (u_char *)op + ino[n];
216 key.size = off - ino[n];
217
218 if (__call_hash(hashp, key.data, key.size) == obucket) {
219 /* Don't switch page */
220 diff = copyto - off;
221 if (diff) {
222 copyto = ino[n + 1] + diff;
223 memmove(op + copyto, op + ino[n + 1],
224 off - ino[n + 1]);
225 ino[ndx] = copyto + ino[n] - ino[n + 1];
226 ino[ndx + 1] = copyto;
227 } else
228 copyto = ino[n + 1];
229 ndx += 2;
230 } else {
231 /* Switch page */
232 val.data = (u_char *)op + ino[n + 1];
233 val.size = ino[n] - ino[n + 1];
234 putpair(np, &key, &val);
235 moved += 2;
236 }
237
238 off = ino[n + 1];
239 }
240
241 /* Now clean up the page */
242 ino[0] -= moved;
243 FREESPACE(ino) = copyto - sizeof(u_int16_t) * (ino[0] + 3);
244 OFFSET(ino) = copyto;
245
246 #ifdef DEBUG3
247 (void)fprintf(stderr, "split %d/%d\n",
248 ((u_int16_t *)np)[0] / 2,
249 ((u_int16_t *)op)[0] / 2);
250 #endif
251 /* unpin both pages */
252 old_bufp->flags &= ~BUF_PIN;
253 new_bufp->flags &= ~BUF_PIN;
254 return (0);
255 }
256
257 /*
258 * Called when we encounter an overflow or big key/data page during split
259 * handling. This is special cased since we have to begin checking whether
260 * the key/data pairs fit on their respective pages and because we may need
261 * overflow pages for both the old and new pages.
262 *
263 * The first page might be a page with regular key/data pairs in which case
264 * we have a regular overflow condition and just need to go on to the next
265 * page or it might be a big key/data pair in which case we need to fix the
266 * big key/data pair.
267 *
268 * Returns:
269 * 0 ==> success
270 * -1 ==> failure
271 */
272 static int
ugly_split(HTAB * hashp,u_int32_t obucket,BUFHEAD * old_bufp,BUFHEAD * new_bufp,int copyto,int moved)273 ugly_split(HTAB *hashp,
274 u_int32_t obucket, /* Same as __split_page. */
275 BUFHEAD *old_bufp,
276 BUFHEAD *new_bufp,
277 int copyto, /* First byte on page which contains key/data values. */
278 int moved) /* Number of pairs moved to new page. */
279 {
280 BUFHEAD *bufp; /* Buffer header for ino */
281 u_int16_t *ino; /* Page keys come off of */
282 u_int16_t *np; /* New page */
283 u_int16_t *op; /* Page keys go on to if they aren't moving */
284
285 BUFHEAD *last_bfp; /* Last buf header OVFL needing to be freed */
286 DBT key, val;
287 SPLIT_RETURN ret;
288 u_int16_t n, off, ov_addr, scopyto;
289 char *cino; /* Character value of ino */
290
291 bufp = old_bufp;
292 ino = (u_int16_t *)old_bufp->page;
293 np = (u_int16_t *)new_bufp->page;
294 op = (u_int16_t *)old_bufp->page;
295 last_bfp = NULL;
296 scopyto = (u_int16_t)copyto; /* ANSI */
297
298 n = ino[0] - 1;
299 while (n < ino[0]) {
300 if (ino[2] < REAL_KEY && ino[2] != OVFLPAGE) {
301 if (__big_split(hashp, old_bufp,
302 new_bufp, bufp, bufp->addr, obucket, &ret))
303 return (-1);
304 old_bufp = ret.oldp;
305 if (!old_bufp)
306 return (-1);
307 op = (u_int16_t *)old_bufp->page;
308 new_bufp = ret.newp;
309 if (!new_bufp)
310 return (-1);
311 np = (u_int16_t *)new_bufp->page;
312 bufp = ret.nextp;
313 if (!bufp)
314 return (0);
315 cino = (char *)bufp->page;
316 ino = (u_int16_t *)cino;
317 last_bfp = ret.nextp;
318 } else if (ino[n + 1] == OVFLPAGE) {
319 ov_addr = ino[n];
320 /*
321 * Fix up the old page -- the extra 2 are the fields
322 * which contained the overflow information.
323 */
324 ino[0] -= (moved + 2);
325 FREESPACE(ino) =
326 scopyto - sizeof(u_int16_t) * (ino[0] + 3);
327 OFFSET(ino) = scopyto;
328
329 bufp = __get_buf(hashp, ov_addr, bufp, 0);
330 if (!bufp)
331 return (-1);
332
333 ino = (u_int16_t *)bufp->page;
334 n = 1;
335 scopyto = hashp->BSIZE;
336 moved = 0;
337
338 if (last_bfp)
339 __free_ovflpage(hashp, last_bfp);
340 last_bfp = bufp;
341 }
342 /* Move regular sized pairs of there are any */
343 off = hashp->BSIZE;
344 for (n = 1; (n < ino[0]) && (ino[n + 1] >= REAL_KEY); n += 2) {
345 cino = (char *)ino;
346 key.data = (u_char *)cino + ino[n];
347 key.size = off - ino[n];
348 val.data = (u_char *)cino + ino[n + 1];
349 val.size = ino[n] - ino[n + 1];
350 off = ino[n + 1];
351
352 if (__call_hash(hashp, key.data, key.size) == obucket) {
353 /* Keep on old page */
354 if (PAIRFITS(op, (&key), (&val)))
355 putpair((char *)op, &key, &val);
356 else {
357 old_bufp =
358 __add_ovflpage(hashp, old_bufp);
359 if (!old_bufp)
360 return (-1);
361 op = (u_int16_t *)old_bufp->page;
362 putpair((char *)op, &key, &val);
363 }
364 old_bufp->flags |= BUF_MOD;
365 } else {
366 /* Move to new page */
367 if (PAIRFITS(np, (&key), (&val)))
368 putpair((char *)np, &key, &val);
369 else {
370 new_bufp =
371 __add_ovflpage(hashp, new_bufp);
372 if (!new_bufp)
373 return (-1);
374 np = (u_int16_t *)new_bufp->page;
375 putpair((char *)np, &key, &val);
376 }
377 new_bufp->flags |= BUF_MOD;
378 }
379 }
380 }
381 if (last_bfp)
382 __free_ovflpage(hashp, last_bfp);
383 return (0);
384 }
385
386 /*
387 * Add the given pair to the page
388 *
389 * Returns:
390 * 0 ==> OK
391 * 1 ==> failure
392 */
393 int
__addel(HTAB * hashp,BUFHEAD * bufp,const DBT * key,const DBT * val)394 __addel(HTAB *hashp, BUFHEAD *bufp, const DBT *key, const DBT *val)
395 {
396 u_int16_t *bp, *sop;
397 int do_expand;
398
399 bp = (u_int16_t *)bufp->page;
400 do_expand = 0;
401 while (bp[0] && (bp[2] < REAL_KEY || bp[bp[0]] < REAL_KEY))
402 /* Exception case */
403 if (bp[2] == FULL_KEY_DATA && bp[0] == 2)
404 /* This is the last page of a big key/data pair
405 and we need to add another page */
406 break;
407 else if (bp[2] < REAL_KEY && bp[bp[0]] != OVFLPAGE) {
408 bufp = __get_buf(hashp, bp[bp[0] - 1], bufp, 0);
409 if (!bufp)
410 return (-1);
411 bp = (u_int16_t *)bufp->page;
412 } else if (bp[bp[0]] != OVFLPAGE) {
413 /* Short key/data pairs, no more pages */
414 break;
415 } else {
416 /* Try to squeeze key on this page */
417 if (bp[2] >= REAL_KEY &&
418 FREESPACE(bp) >= PAIRSIZE(key, val)) {
419 squeeze_key(bp, key, val);
420 goto stats;
421 } else {
422 bufp = __get_buf(hashp, bp[bp[0] - 1], bufp, 0);
423 if (!bufp)
424 return (-1);
425 bp = (u_int16_t *)bufp->page;
426 }
427 }
428
429 if (PAIRFITS(bp, key, val))
430 putpair(bufp->page, key, val);
431 else {
432 do_expand = 1;
433 bufp = __add_ovflpage(hashp, bufp);
434 if (!bufp)
435 return (-1);
436 sop = (u_int16_t *)bufp->page;
437
438 if (PAIRFITS(sop, key, val))
439 putpair((char *)sop, key, val);
440 else
441 if (__big_insert(hashp, bufp, key, val))
442 return (-1);
443 }
444 stats:
445 bufp->flags |= BUF_MOD;
446 /*
447 * If the average number of keys per bucket exceeds the fill factor,
448 * expand the table.
449 */
450 hashp->NKEYS++;
451 if (do_expand ||
452 (hashp->NKEYS / (hashp->MAX_BUCKET + 1) > hashp->FFACTOR))
453 return (__expand_table(hashp));
454 return (0);
455 }
456
457 /*
458 *
459 * Returns:
460 * pointer on success
461 * NULL on error
462 */
463 BUFHEAD *
__add_ovflpage(HTAB * hashp,BUFHEAD * bufp)464 __add_ovflpage(HTAB *hashp, BUFHEAD *bufp)
465 {
466 u_int16_t *sp, ndx, ovfl_num;
467 #ifdef DEBUG1
468 int tmp1, tmp2;
469 #endif
470 sp = (u_int16_t *)bufp->page;
471
472 /* Check if we are dynamically determining the fill factor */
473 if (hashp->FFACTOR == DEF_FFACTOR) {
474 hashp->FFACTOR = sp[0] >> 1;
475 if (hashp->FFACTOR < MIN_FFACTOR)
476 hashp->FFACTOR = MIN_FFACTOR;
477 }
478 bufp->flags |= BUF_MOD;
479 ovfl_num = overflow_page(hashp);
480 #ifdef DEBUG1
481 tmp1 = bufp->addr;
482 tmp2 = bufp->ovfl ? bufp->ovfl->addr : 0;
483 #endif
484 if (!ovfl_num || !(bufp->ovfl = __get_buf(hashp, ovfl_num, bufp, 1)))
485 return (NULL);
486 bufp->ovfl->flags |= BUF_MOD;
487 #ifdef DEBUG1
488 (void)fprintf(stderr, "ADDOVFLPAGE: %d->ovfl was %d is now %d\n",
489 tmp1, tmp2, bufp->ovfl->addr);
490 #endif
491 ndx = sp[0];
492 /*
493 * Since a pair is allocated on a page only if there's room to add
494 * an overflow page, we know that the OVFL information will fit on
495 * the page.
496 */
497 sp[ndx + 4] = OFFSET(sp);
498 sp[ndx + 3] = FREESPACE(sp) - OVFLSIZE;
499 sp[ndx + 1] = ovfl_num;
500 sp[ndx + 2] = OVFLPAGE;
501 sp[0] = ndx + 2;
502 #ifdef HASH_STATISTICS
503 hash_overflows++;
504 #endif
505 return (bufp->ovfl);
506 }
507
508 /*
509 * Returns:
510 * 0 indicates SUCCESS
511 * -1 indicates FAILURE
512 */
513 int
__get_page(HTAB * hashp,char * p,u_int32_t bucket,int is_bucket,int is_disk,int is_bitmap)514 __get_page(HTAB *hashp, char *p, u_int32_t bucket, int is_bucket, int is_disk,
515 int is_bitmap)
516 {
517 int fd, page, size, rsize;
518 u_int16_t *bp;
519
520 fd = hashp->fp;
521 size = hashp->BSIZE;
522
523 if ((fd == -1) || !is_disk) {
524 PAGE_INIT(p);
525 return (0);
526 }
527 if (is_bucket)
528 page = BUCKET_TO_PAGE(bucket);
529 else
530 page = OADDR_TO_PAGE(bucket);
531 if ((rsize = pread(fd, p, size, (off_t)page << hashp->BSHIFT)) == -1)
532 return (-1);
533 bp = (u_int16_t *)p;
534 if (!rsize)
535 bp[0] = 0; /* We hit the EOF, so initialize a new page */
536 else
537 if (rsize != size) {
538 errno = EFTYPE;
539 return (-1);
540 }
541 if (!is_bitmap && !bp[0]) {
542 PAGE_INIT(p);
543 } else
544 if (hashp->LORDER != BYTE_ORDER) {
545 int i, max;
546
547 if (is_bitmap) {
548 max = hashp->BSIZE >> 2; /* divide by 4 */
549 for (i = 0; i < max; i++)
550 M_32_SWAP(((int *)p)[i]);
551 } else {
552 M_16_SWAP(bp[0]);
553 max = bp[0] + 2;
554 for (i = 1; i <= max; i++)
555 M_16_SWAP(bp[i]);
556 }
557 }
558 return (0);
559 }
560
561 /*
562 * Write page p to disk
563 *
564 * Returns:
565 * 0 ==> OK
566 * -1 ==>failure
567 */
568 int
__put_page(HTAB * hashp,char * p,u_int32_t bucket,int is_bucket,int is_bitmap)569 __put_page(HTAB *hashp, char *p, u_int32_t bucket, int is_bucket, int is_bitmap)
570 {
571 int fd, page, size;
572 ssize_t wsize;
573 char pbuf[MAX_BSIZE];
574
575 size = hashp->BSIZE;
576 if ((hashp->fp == -1) && open_temp(hashp))
577 return (-1);
578 fd = hashp->fp;
579
580 if (hashp->LORDER != BYTE_ORDER) {
581 int i, max;
582
583 memcpy(pbuf, p, size);
584 if (is_bitmap) {
585 max = hashp->BSIZE >> 2; /* divide by 4 */
586 for (i = 0; i < max; i++)
587 M_32_SWAP(((int *)pbuf)[i]);
588 } else {
589 uint16_t *bp = (uint16_t *)(void *)pbuf;
590 max = bp[0] + 2;
591 for (i = 0; i <= max; i++)
592 M_16_SWAP(bp[i]);
593 }
594 p = pbuf;
595 }
596 if (is_bucket)
597 page = BUCKET_TO_PAGE(bucket);
598 else
599 page = OADDR_TO_PAGE(bucket);
600 if ((wsize = pwrite(fd, p, size, (off_t)page << hashp->BSHIFT)) == -1)
601 /* Errno is set */
602 return (-1);
603 if (wsize != size) {
604 errno = EFTYPE;
605 return (-1);
606 }
607 return (0);
608 }
609
610 #define BYTE_MASK ((1 << INT_BYTE_SHIFT) -1)
611 /*
612 * Initialize a new bitmap page. Bitmap pages are left in memory
613 * once they are read in.
614 */
615 int
__ibitmap(HTAB * hashp,int pnum,int nbits,int ndx)616 __ibitmap(HTAB *hashp, int pnum, int nbits, int ndx)
617 {
618 u_int32_t *ip;
619 int clearbytes, clearints;
620
621 if ((ip = (u_int32_t *)malloc(hashp->BSIZE)) == NULL)
622 return (1);
623 hashp->nmaps++;
624 clearints = ((nbits - 1) >> INT_BYTE_SHIFT) + 1;
625 clearbytes = clearints << INT_TO_BYTE;
626 (void)memset((char *)ip, 0, clearbytes);
627 (void)memset(((char *)ip) + clearbytes, 0xFF,
628 hashp->BSIZE - clearbytes);
629 ip[clearints - 1] = ALL_SET << (nbits & BYTE_MASK);
630 SETBIT(ip, 0);
631 hashp->BITMAPS[ndx] = (u_int16_t)pnum;
632 hashp->mapp[ndx] = ip;
633 return (0);
634 }
635
636 static u_int32_t
first_free(u_int32_t map)637 first_free(u_int32_t map)
638 {
639 u_int32_t i, mask;
640
641 mask = 0x1;
642 for (i = 0; i < BITS_PER_MAP; i++) {
643 if (!(mask & map))
644 return (i);
645 mask = mask << 1;
646 }
647 return (i);
648 }
649
650 static u_int16_t
overflow_page(HTAB * hashp)651 overflow_page(HTAB *hashp)
652 {
653 u_int32_t *freep;
654 int max_free, offset, splitnum;
655 u_int16_t addr;
656 int bit, first_page, free_bit, free_page, i, in_use_bits, j;
657 #ifdef DEBUG2
658 int tmp1, tmp2;
659 #endif
660 splitnum = hashp->OVFL_POINT;
661 max_free = hashp->SPARES[splitnum];
662
663 free_page = (max_free - 1) >> (hashp->BSHIFT + BYTE_SHIFT);
664 free_bit = (max_free - 1) & ((hashp->BSIZE << BYTE_SHIFT) - 1);
665
666 /* Look through all the free maps to find the first free block */
667 first_page = hashp->LAST_FREED >>(hashp->BSHIFT + BYTE_SHIFT);
668 for ( i = first_page; i <= free_page; i++ ) {
669 if (!(freep = (u_int32_t *)hashp->mapp[i]) &&
670 !(freep = fetch_bitmap(hashp, i)))
671 return (0);
672 if (i == free_page)
673 in_use_bits = free_bit;
674 else
675 in_use_bits = (hashp->BSIZE << BYTE_SHIFT) - 1;
676
677 if (i == first_page) {
678 bit = hashp->LAST_FREED &
679 ((hashp->BSIZE << BYTE_SHIFT) - 1);
680 j = bit / BITS_PER_MAP;
681 bit = rounddown2(bit, BITS_PER_MAP);
682 } else {
683 bit = 0;
684 j = 0;
685 }
686 for (; bit <= in_use_bits; j++, bit += BITS_PER_MAP)
687 if (freep[j] != ALL_SET)
688 goto found;
689 }
690
691 /* No Free Page Found */
692 hashp->LAST_FREED = hashp->SPARES[splitnum];
693 hashp->SPARES[splitnum]++;
694 offset = hashp->SPARES[splitnum] -
695 (splitnum ? hashp->SPARES[splitnum - 1] : 0);
696
697 #define OVMSG "HASH: Out of overflow pages. Increase page size\n"
698 if (offset > SPLITMASK) {
699 if (++splitnum >= NCACHED) {
700 (void)_write(STDERR_FILENO, OVMSG, sizeof(OVMSG) - 1);
701 errno = EFBIG;
702 return (0);
703 }
704 hashp->OVFL_POINT = splitnum;
705 hashp->SPARES[splitnum] = hashp->SPARES[splitnum-1];
706 hashp->SPARES[splitnum-1]--;
707 offset = 1;
708 }
709
710 /* Check if we need to allocate a new bitmap page */
711 if (free_bit == (hashp->BSIZE << BYTE_SHIFT) - 1) {
712 free_page++;
713 if (free_page >= NCACHED) {
714 (void)_write(STDERR_FILENO, OVMSG, sizeof(OVMSG) - 1);
715 errno = EFBIG;
716 return (0);
717 }
718 /*
719 * This is tricky. The 1 indicates that you want the new page
720 * allocated with 1 clear bit. Actually, you are going to
721 * allocate 2 pages from this map. The first is going to be
722 * the map page, the second is the overflow page we were
723 * looking for. The init_bitmap routine automatically, sets
724 * the first bit of itself to indicate that the bitmap itself
725 * is in use. We would explicitly set the second bit, but
726 * don't have to if we tell init_bitmap not to leave it clear
727 * in the first place.
728 */
729 if (__ibitmap(hashp,
730 (int)OADDR_OF(splitnum, offset), 1, free_page))
731 return (0);
732 hashp->SPARES[splitnum]++;
733 #ifdef DEBUG2
734 free_bit = 2;
735 #endif
736 offset++;
737 if (offset > SPLITMASK) {
738 if (++splitnum >= NCACHED) {
739 (void)_write(STDERR_FILENO, OVMSG,
740 sizeof(OVMSG) - 1);
741 errno = EFBIG;
742 return (0);
743 }
744 hashp->OVFL_POINT = splitnum;
745 hashp->SPARES[splitnum] = hashp->SPARES[splitnum-1];
746 hashp->SPARES[splitnum-1]--;
747 offset = 0;
748 }
749 } else {
750 /*
751 * Free_bit addresses the last used bit. Bump it to address
752 * the first available bit.
753 */
754 free_bit++;
755 SETBIT(freep, free_bit);
756 }
757
758 /* Calculate address of the new overflow page */
759 addr = OADDR_OF(splitnum, offset);
760 #ifdef DEBUG2
761 (void)fprintf(stderr, "OVERFLOW_PAGE: ADDR: %d BIT: %d PAGE %d\n",
762 addr, free_bit, free_page);
763 #endif
764 return (addr);
765
766 found:
767 bit = bit + first_free(freep[j]);
768 SETBIT(freep, bit);
769 #ifdef DEBUG2
770 tmp1 = bit;
771 tmp2 = i;
772 #endif
773 /*
774 * Bits are addressed starting with 0, but overflow pages are addressed
775 * beginning at 1. Bit is a bit addressnumber, so we need to increment
776 * it to convert it to a page number.
777 */
778 bit = 1 + bit + (i * (hashp->BSIZE << BYTE_SHIFT));
779 if (bit >= hashp->LAST_FREED)
780 hashp->LAST_FREED = bit - 1;
781
782 /* Calculate the split number for this page */
783 for (i = 0; (i < splitnum) && (bit > hashp->SPARES[i]); i++);
784 offset = (i ? bit - hashp->SPARES[i - 1] : bit);
785 if (offset >= SPLITMASK) {
786 (void)_write(STDERR_FILENO, OVMSG, sizeof(OVMSG) - 1);
787 errno = EFBIG;
788 return (0); /* Out of overflow pages */
789 }
790 addr = OADDR_OF(i, offset);
791 #ifdef DEBUG2
792 (void)fprintf(stderr, "OVERFLOW_PAGE: ADDR: %d BIT: %d PAGE %d\n",
793 addr, tmp1, tmp2);
794 #endif
795
796 /* Allocate and return the overflow page */
797 return (addr);
798 }
799
800 /*
801 * Mark this overflow page as free.
802 */
803 void
__free_ovflpage(HTAB * hashp,BUFHEAD * obufp)804 __free_ovflpage(HTAB *hashp, BUFHEAD *obufp)
805 {
806 u_int16_t addr;
807 u_int32_t *freep;
808 int bit_address, free_page, free_bit;
809 u_int16_t ndx;
810
811 addr = obufp->addr;
812 #ifdef DEBUG1
813 (void)fprintf(stderr, "Freeing %d\n", addr);
814 #endif
815 ndx = (((u_int16_t)addr) >> SPLITSHIFT);
816 bit_address =
817 (ndx ? hashp->SPARES[ndx - 1] : 0) + (addr & SPLITMASK) - 1;
818 if (bit_address < hashp->LAST_FREED)
819 hashp->LAST_FREED = bit_address;
820 free_page = (bit_address >> (hashp->BSHIFT + BYTE_SHIFT));
821 free_bit = bit_address & ((hashp->BSIZE << BYTE_SHIFT) - 1);
822
823 if (!(freep = hashp->mapp[free_page]))
824 freep = fetch_bitmap(hashp, free_page);
825 #ifdef DEBUG
826 /*
827 * This had better never happen. It means we tried to read a bitmap
828 * that has already had overflow pages allocated off it, and we
829 * failed to read it from the file.
830 */
831 if (!freep)
832 assert(0);
833 #endif
834 CLRBIT(freep, free_bit);
835 #ifdef DEBUG2
836 (void)fprintf(stderr, "FREE_OVFLPAGE: ADDR: %d BIT: %d PAGE %d\n",
837 obufp->addr, free_bit, free_page);
838 #endif
839 __reclaim_buf(hashp, obufp);
840 }
841
842 /*
843 * Returns:
844 * 0 success
845 * -1 failure
846 */
847 static int
open_temp(HTAB * hashp)848 open_temp(HTAB *hashp)
849 {
850 sigset_t set, oset;
851 int len;
852 char *envtmp;
853 char path[MAXPATHLEN];
854
855 envtmp = secure_getenv("TMPDIR");
856 len = snprintf(path,
857 sizeof(path), "%s/_hash.XXXXXX", envtmp ? envtmp : "/tmp");
858 if (len < 0 || len >= (int)sizeof(path)) {
859 errno = ENAMETOOLONG;
860 return (-1);
861 }
862
863 /* Block signals; make sure file goes away at process exit. */
864 (void)sigfillset(&set);
865 (void)__libc_sigprocmask(SIG_BLOCK, &set, &oset);
866 if ((hashp->fp = mkostemp(path, O_CLOEXEC)) != -1)
867 (void)unlink(path);
868 (void)__libc_sigprocmask(SIG_SETMASK, &oset, (sigset_t *)NULL);
869 return (hashp->fp != -1 ? 0 : -1);
870 }
871
872 /*
873 * We have to know that the key will fit, but the last entry on the page is
874 * an overflow pair, so we need to shift things.
875 */
876 static void
squeeze_key(u_int16_t * sp,const DBT * key,const DBT * val)877 squeeze_key(u_int16_t *sp, const DBT *key, const DBT *val)
878 {
879 char *p;
880 u_int16_t free_space, n, off, pageno;
881
882 p = (char *)sp;
883 n = sp[0];
884 free_space = FREESPACE(sp);
885 off = OFFSET(sp);
886
887 pageno = sp[n - 1];
888 off -= key->size;
889 sp[n - 1] = off;
890 memmove(p + off, key->data, key->size);
891 off -= val->size;
892 sp[n] = off;
893 memmove(p + off, val->data, val->size);
894 sp[0] = n + 2;
895 sp[n + 1] = pageno;
896 sp[n + 2] = OVFLPAGE;
897 FREESPACE(sp) = free_space - PAIRSIZE(key, val);
898 OFFSET(sp) = off;
899 }
900
901 static u_int32_t *
fetch_bitmap(HTAB * hashp,int ndx)902 fetch_bitmap(HTAB *hashp, int ndx)
903 {
904 if (ndx >= hashp->nmaps)
905 return (NULL);
906 if ((hashp->mapp[ndx] = (u_int32_t *)malloc(hashp->BSIZE)) == NULL)
907 return (NULL);
908 if (__get_page(hashp,
909 (char *)hashp->mapp[ndx], hashp->BITMAPS[ndx], 0, 1, 1)) {
910 free(hashp->mapp[ndx]);
911 return (NULL);
912 }
913 return (hashp->mapp[ndx]);
914 }
915
916 #ifdef DEBUG4
917 int
print_chain(int addr)918 print_chain(int addr)
919 {
920 BUFHEAD *bufp;
921 short *bp, oaddr;
922
923 (void)fprintf(stderr, "%d ", addr);
924 bufp = __get_buf(hashp, addr, NULL, 0);
925 bp = (short *)bufp->page;
926 while (bp[0] && ((bp[bp[0]] == OVFLPAGE) ||
927 ((bp[0] > 2) && bp[2] < REAL_KEY))) {
928 oaddr = bp[bp[0] - 1];
929 (void)fprintf(stderr, "%d ", (int)oaddr);
930 bufp = __get_buf(hashp, (int)oaddr, bufp, 0);
931 bp = (short *)bufp->page;
932 }
933 (void)fprintf(stderr, "\n");
934 }
935 #endif
936