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 #if defined(LIBC_SCCS) && !defined(lint)
36 static char sccsid[] = "@(#)hash_page.c 8.7 (Berkeley) 8/16/94";
37 #endif /* LIBC_SCCS and not lint */
38 #include <sys/cdefs.h>
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 #include "libc_private.h"
70
71 #include <db.h>
72 #include "hash.h"
73 #include "page.h"
74 #include "extern.h"
75
76 static u_int32_t *fetch_bitmap(HTAB *, int);
77 static u_int32_t first_free(u_int32_t);
78 static int open_temp(HTAB *);
79 static u_int16_t overflow_page(HTAB *);
80 static void putpair(char *, const DBT *, const DBT *);
81 static void squeeze_key(u_int16_t *, const DBT *, const DBT *);
82 static int ugly_split(HTAB *, u_int32_t, BUFHEAD *, BUFHEAD *, int, int);
83
84 #define PAGE_INIT(P) { \
85 ((u_int16_t *)(P))[0] = 0; \
86 ((u_int16_t *)(P))[1] = hashp->BSIZE - 3 * sizeof(u_int16_t); \
87 ((u_int16_t *)(P))[2] = hashp->BSIZE; \
88 }
89
90 /*
91 * This is called AFTER we have verified that there is room on the page for
92 * the pair (PAIRFITS has returned true) so we go right ahead and start moving
93 * stuff on.
94 */
95 static void
putpair(char * p,const DBT * key,const DBT * val)96 putpair(char *p, const DBT *key, const DBT *val)
97 {
98 u_int16_t *bp, n, off;
99
100 bp = (u_int16_t *)p;
101
102 /* Enter the key first. */
103 n = bp[0];
104
105 off = OFFSET(bp) - key->size;
106 memmove(p + off, key->data, key->size);
107 bp[++n] = off;
108
109 /* Now the data. */
110 off -= val->size;
111 memmove(p + off, val->data, val->size);
112 bp[++n] = off;
113
114 /* Adjust page info. */
115 bp[0] = n;
116 bp[n + 1] = off - ((n + 3) * sizeof(u_int16_t));
117 bp[n + 2] = off;
118 }
119
120 /*
121 * Returns:
122 * 0 OK
123 * -1 error
124 */
125 int
__delpair(HTAB * hashp,BUFHEAD * bufp,int ndx)126 __delpair(HTAB *hashp, BUFHEAD *bufp, int ndx)
127 {
128 u_int16_t *bp, newoff, pairlen;
129 int n;
130
131 bp = (u_int16_t *)bufp->page;
132 n = bp[0];
133
134 if (bp[ndx + 1] < REAL_KEY)
135 return (__big_delete(hashp, bufp));
136 if (ndx != 1)
137 newoff = bp[ndx - 1];
138 else
139 newoff = hashp->BSIZE;
140 pairlen = newoff - bp[ndx + 1];
141
142 if (ndx != (n - 1)) {
143 /* Hard Case -- need to shuffle keys */
144 int i;
145 char *src = bufp->page + (int)OFFSET(bp);
146 char *dst = src + (int)pairlen;
147 memmove(dst, src, bp[ndx + 1] - OFFSET(bp));
148
149 /* Now adjust the pointers */
150 for (i = ndx + 2; i <= n; i += 2) {
151 if (bp[i + 1] == OVFLPAGE) {
152 bp[i - 2] = bp[i];
153 bp[i - 1] = bp[i + 1];
154 } else {
155 bp[i - 2] = bp[i] + pairlen;
156 bp[i - 1] = bp[i + 1] + pairlen;
157 }
158 }
159 if (ndx == hashp->cndx) {
160 /*
161 * We just removed pair we were "pointing" to.
162 * By moving back the cndx we ensure subsequent
163 * hash_seq() calls won't skip over any entries.
164 */
165 hashp->cndx -= 2;
166 }
167 }
168 /* Finally adjust the page data */
169 bp[n] = OFFSET(bp) + pairlen;
170 bp[n - 1] = bp[n + 1] + pairlen + 2 * sizeof(u_int16_t);
171 bp[0] = n - 2;
172 hashp->NKEYS--;
173
174 bufp->flags |= BUF_MOD;
175 return (0);
176 }
177 /*
178 * Returns:
179 * 0 ==> OK
180 * -1 ==> Error
181 */
182 int
__split_page(HTAB * hashp,u_int32_t obucket,u_int32_t nbucket)183 __split_page(HTAB *hashp, u_int32_t obucket, u_int32_t nbucket)
184 {
185 BUFHEAD *new_bufp, *old_bufp;
186 u_int16_t *ino;
187 char *np;
188 DBT key, val;
189 int n, ndx, retval;
190 u_int16_t copyto, diff, off, moved;
191 char *op;
192
193 copyto = (u_int16_t)hashp->BSIZE;
194 off = (u_int16_t)hashp->BSIZE;
195 old_bufp = __get_buf(hashp, obucket, NULL, 0);
196 if (old_bufp == NULL)
197 return (-1);
198 new_bufp = __get_buf(hashp, nbucket, NULL, 0);
199 if (new_bufp == NULL)
200 return (-1);
201
202 old_bufp->flags |= (BUF_MOD | BUF_PIN);
203 new_bufp->flags |= (BUF_MOD | BUF_PIN);
204
205 ino = (u_int16_t *)(op = old_bufp->page);
206 np = new_bufp->page;
207
208 moved = 0;
209
210 for (n = 1, ndx = 1; n < ino[0]; n += 2) {
211 if (ino[n + 1] < REAL_KEY) {
212 retval = ugly_split(hashp, obucket, old_bufp, new_bufp,
213 (int)copyto, (int)moved);
214 old_bufp->flags &= ~BUF_PIN;
215 new_bufp->flags &= ~BUF_PIN;
216 return (retval);
217
218 }
219 key.data = (u_char *)op + ino[n];
220 key.size = off - ino[n];
221
222 if (__call_hash(hashp, key.data, key.size) == obucket) {
223 /* Don't switch page */
224 diff = copyto - off;
225 if (diff) {
226 copyto = ino[n + 1] + diff;
227 memmove(op + copyto, op + ino[n + 1],
228 off - ino[n + 1]);
229 ino[ndx] = copyto + ino[n] - ino[n + 1];
230 ino[ndx + 1] = copyto;
231 } else
232 copyto = ino[n + 1];
233 ndx += 2;
234 } else {
235 /* Switch page */
236 val.data = (u_char *)op + ino[n + 1];
237 val.size = ino[n] - ino[n + 1];
238 putpair(np, &key, &val);
239 moved += 2;
240 }
241
242 off = ino[n + 1];
243 }
244
245 /* Now clean up the page */
246 ino[0] -= moved;
247 FREESPACE(ino) = copyto - sizeof(u_int16_t) * (ino[0] + 3);
248 OFFSET(ino) = copyto;
249
250 #ifdef DEBUG3
251 (void)fprintf(stderr, "split %d/%d\n",
252 ((u_int16_t *)np)[0] / 2,
253 ((u_int16_t *)op)[0] / 2);
254 #endif
255 /* unpin both pages */
256 old_bufp->flags &= ~BUF_PIN;
257 new_bufp->flags &= ~BUF_PIN;
258 return (0);
259 }
260
261 /*
262 * Called when we encounter an overflow or big key/data page during split
263 * handling. This is special cased since we have to begin checking whether
264 * the key/data pairs fit on their respective pages and because we may need
265 * overflow pages for both the old and new pages.
266 *
267 * The first page might be a page with regular key/data pairs in which case
268 * we have a regular overflow condition and just need to go on to the next
269 * page or it might be a big key/data pair in which case we need to fix the
270 * big key/data pair.
271 *
272 * Returns:
273 * 0 ==> success
274 * -1 ==> failure
275 */
276 static int
ugly_split(HTAB * hashp,u_int32_t obucket,BUFHEAD * old_bufp,BUFHEAD * new_bufp,int copyto,int moved)277 ugly_split(HTAB *hashp,
278 u_int32_t obucket, /* Same as __split_page. */
279 BUFHEAD *old_bufp,
280 BUFHEAD *new_bufp,
281 int copyto, /* First byte on page which contains key/data values. */
282 int moved) /* Number of pairs moved to new page. */
283 {
284 BUFHEAD *bufp; /* Buffer header for ino */
285 u_int16_t *ino; /* Page keys come off of */
286 u_int16_t *np; /* New page */
287 u_int16_t *op; /* Page keys go on to if they aren't moving */
288
289 BUFHEAD *last_bfp; /* Last buf header OVFL needing to be freed */
290 DBT key, val;
291 SPLIT_RETURN ret;
292 u_int16_t n, off, ov_addr, scopyto;
293 char *cino; /* Character value of ino */
294
295 bufp = old_bufp;
296 ino = (u_int16_t *)old_bufp->page;
297 np = (u_int16_t *)new_bufp->page;
298 op = (u_int16_t *)old_bufp->page;
299 last_bfp = NULL;
300 scopyto = (u_int16_t)copyto; /* ANSI */
301
302 n = ino[0] - 1;
303 while (n < ino[0]) {
304 if (ino[2] < REAL_KEY && ino[2] != OVFLPAGE) {
305 if (__big_split(hashp, old_bufp,
306 new_bufp, bufp, bufp->addr, obucket, &ret))
307 return (-1);
308 old_bufp = ret.oldp;
309 if (!old_bufp)
310 return (-1);
311 op = (u_int16_t *)old_bufp->page;
312 new_bufp = ret.newp;
313 if (!new_bufp)
314 return (-1);
315 np = (u_int16_t *)new_bufp->page;
316 bufp = ret.nextp;
317 if (!bufp)
318 return (0);
319 cino = (char *)bufp->page;
320 ino = (u_int16_t *)cino;
321 last_bfp = ret.nextp;
322 } else if (ino[n + 1] == OVFLPAGE) {
323 ov_addr = ino[n];
324 /*
325 * Fix up the old page -- the extra 2 are the fields
326 * which contained the overflow information.
327 */
328 ino[0] -= (moved + 2);
329 FREESPACE(ino) =
330 scopyto - sizeof(u_int16_t) * (ino[0] + 3);
331 OFFSET(ino) = scopyto;
332
333 bufp = __get_buf(hashp, ov_addr, bufp, 0);
334 if (!bufp)
335 return (-1);
336
337 ino = (u_int16_t *)bufp->page;
338 n = 1;
339 scopyto = hashp->BSIZE;
340 moved = 0;
341
342 if (last_bfp)
343 __free_ovflpage(hashp, last_bfp);
344 last_bfp = bufp;
345 }
346 /* Move regular sized pairs of there are any */
347 off = hashp->BSIZE;
348 for (n = 1; (n < ino[0]) && (ino[n + 1] >= REAL_KEY); n += 2) {
349 cino = (char *)ino;
350 key.data = (u_char *)cino + ino[n];
351 key.size = off - ino[n];
352 val.data = (u_char *)cino + ino[n + 1];
353 val.size = ino[n] - ino[n + 1];
354 off = ino[n + 1];
355
356 if (__call_hash(hashp, key.data, key.size) == obucket) {
357 /* Keep on old page */
358 if (PAIRFITS(op, (&key), (&val)))
359 putpair((char *)op, &key, &val);
360 else {
361 old_bufp =
362 __add_ovflpage(hashp, old_bufp);
363 if (!old_bufp)
364 return (-1);
365 op = (u_int16_t *)old_bufp->page;
366 putpair((char *)op, &key, &val);
367 }
368 old_bufp->flags |= BUF_MOD;
369 } else {
370 /* Move to new page */
371 if (PAIRFITS(np, (&key), (&val)))
372 putpair((char *)np, &key, &val);
373 else {
374 new_bufp =
375 __add_ovflpage(hashp, new_bufp);
376 if (!new_bufp)
377 return (-1);
378 np = (u_int16_t *)new_bufp->page;
379 putpair((char *)np, &key, &val);
380 }
381 new_bufp->flags |= BUF_MOD;
382 }
383 }
384 }
385 if (last_bfp)
386 __free_ovflpage(hashp, last_bfp);
387 return (0);
388 }
389
390 /*
391 * Add the given pair to the page
392 *
393 * Returns:
394 * 0 ==> OK
395 * 1 ==> failure
396 */
397 int
__addel(HTAB * hashp,BUFHEAD * bufp,const DBT * key,const DBT * val)398 __addel(HTAB *hashp, BUFHEAD *bufp, const DBT *key, const DBT *val)
399 {
400 u_int16_t *bp, *sop;
401 int do_expand;
402
403 bp = (u_int16_t *)bufp->page;
404 do_expand = 0;
405 while (bp[0] && (bp[2] < REAL_KEY || bp[bp[0]] < REAL_KEY))
406 /* Exception case */
407 if (bp[2] == FULL_KEY_DATA && bp[0] == 2)
408 /* This is the last page of a big key/data pair
409 and we need to add another page */
410 break;
411 else if (bp[2] < REAL_KEY && bp[bp[0]] != OVFLPAGE) {
412 bufp = __get_buf(hashp, bp[bp[0] - 1], bufp, 0);
413 if (!bufp)
414 return (-1);
415 bp = (u_int16_t *)bufp->page;
416 } else if (bp[bp[0]] != OVFLPAGE) {
417 /* Short key/data pairs, no more pages */
418 break;
419 } else {
420 /* Try to squeeze key on this page */
421 if (bp[2] >= REAL_KEY &&
422 FREESPACE(bp) >= PAIRSIZE(key, val)) {
423 squeeze_key(bp, key, val);
424 goto stats;
425 } else {
426 bufp = __get_buf(hashp, bp[bp[0] - 1], bufp, 0);
427 if (!bufp)
428 return (-1);
429 bp = (u_int16_t *)bufp->page;
430 }
431 }
432
433 if (PAIRFITS(bp, key, val))
434 putpair(bufp->page, key, val);
435 else {
436 do_expand = 1;
437 bufp = __add_ovflpage(hashp, bufp);
438 if (!bufp)
439 return (-1);
440 sop = (u_int16_t *)bufp->page;
441
442 if (PAIRFITS(sop, key, val))
443 putpair((char *)sop, key, val);
444 else
445 if (__big_insert(hashp, bufp, key, val))
446 return (-1);
447 }
448 stats:
449 bufp->flags |= BUF_MOD;
450 /*
451 * If the average number of keys per bucket exceeds the fill factor,
452 * expand the table.
453 */
454 hashp->NKEYS++;
455 if (do_expand ||
456 (hashp->NKEYS / (hashp->MAX_BUCKET + 1) > hashp->FFACTOR))
457 return (__expand_table(hashp));
458 return (0);
459 }
460
461 /*
462 *
463 * Returns:
464 * pointer on success
465 * NULL on error
466 */
467 BUFHEAD *
__add_ovflpage(HTAB * hashp,BUFHEAD * bufp)468 __add_ovflpage(HTAB *hashp, BUFHEAD *bufp)
469 {
470 u_int16_t *sp, ndx, ovfl_num;
471 #ifdef DEBUG1
472 int tmp1, tmp2;
473 #endif
474 sp = (u_int16_t *)bufp->page;
475
476 /* Check if we are dynamically determining the fill factor */
477 if (hashp->FFACTOR == DEF_FFACTOR) {
478 hashp->FFACTOR = sp[0] >> 1;
479 if (hashp->FFACTOR < MIN_FFACTOR)
480 hashp->FFACTOR = MIN_FFACTOR;
481 }
482 bufp->flags |= BUF_MOD;
483 ovfl_num = overflow_page(hashp);
484 #ifdef DEBUG1
485 tmp1 = bufp->addr;
486 tmp2 = bufp->ovfl ? bufp->ovfl->addr : 0;
487 #endif
488 if (!ovfl_num || !(bufp->ovfl = __get_buf(hashp, ovfl_num, bufp, 1)))
489 return (NULL);
490 bufp->ovfl->flags |= BUF_MOD;
491 #ifdef DEBUG1
492 (void)fprintf(stderr, "ADDOVFLPAGE: %d->ovfl was %d is now %d\n",
493 tmp1, tmp2, bufp->ovfl->addr);
494 #endif
495 ndx = sp[0];
496 /*
497 * Since a pair is allocated on a page only if there's room to add
498 * an overflow page, we know that the OVFL information will fit on
499 * the page.
500 */
501 sp[ndx + 4] = OFFSET(sp);
502 sp[ndx + 3] = FREESPACE(sp) - OVFLSIZE;
503 sp[ndx + 1] = ovfl_num;
504 sp[ndx + 2] = OVFLPAGE;
505 sp[0] = ndx + 2;
506 #ifdef HASH_STATISTICS
507 hash_overflows++;
508 #endif
509 return (bufp->ovfl);
510 }
511
512 /*
513 * Returns:
514 * 0 indicates SUCCESS
515 * -1 indicates FAILURE
516 */
517 int
__get_page(HTAB * hashp,char * p,u_int32_t bucket,int is_bucket,int is_disk,int is_bitmap)518 __get_page(HTAB *hashp, char *p, u_int32_t bucket, int is_bucket, int is_disk,
519 int is_bitmap)
520 {
521 int fd, page, size, rsize;
522 u_int16_t *bp;
523
524 fd = hashp->fp;
525 size = hashp->BSIZE;
526
527 if ((fd == -1) || !is_disk) {
528 PAGE_INIT(p);
529 return (0);
530 }
531 if (is_bucket)
532 page = BUCKET_TO_PAGE(bucket);
533 else
534 page = OADDR_TO_PAGE(bucket);
535 if ((rsize = pread(fd, p, size, (off_t)page << hashp->BSHIFT)) == -1)
536 return (-1);
537 bp = (u_int16_t *)p;
538 if (!rsize)
539 bp[0] = 0; /* We hit the EOF, so initialize a new page */
540 else
541 if (rsize != size) {
542 errno = EFTYPE;
543 return (-1);
544 }
545 if (!is_bitmap && !bp[0]) {
546 PAGE_INIT(p);
547 } else
548 if (hashp->LORDER != BYTE_ORDER) {
549 int i, max;
550
551 if (is_bitmap) {
552 max = hashp->BSIZE >> 2; /* divide by 4 */
553 for (i = 0; i < max; i++)
554 M_32_SWAP(((int *)p)[i]);
555 } else {
556 M_16_SWAP(bp[0]);
557 max = bp[0] + 2;
558 for (i = 1; i <= max; i++)
559 M_16_SWAP(bp[i]);
560 }
561 }
562 return (0);
563 }
564
565 /*
566 * Write page p to disk
567 *
568 * Returns:
569 * 0 ==> OK
570 * -1 ==>failure
571 */
572 int
__put_page(HTAB * hashp,char * p,u_int32_t bucket,int is_bucket,int is_bitmap)573 __put_page(HTAB *hashp, char *p, u_int32_t bucket, int is_bucket, int is_bitmap)
574 {
575 int fd, page, size;
576 ssize_t wsize;
577 char pbuf[MAX_BSIZE];
578
579 size = hashp->BSIZE;
580 if ((hashp->fp == -1) && open_temp(hashp))
581 return (-1);
582 fd = hashp->fp;
583
584 if (hashp->LORDER != BYTE_ORDER) {
585 int i, max;
586
587 memcpy(pbuf, p, size);
588 if (is_bitmap) {
589 max = hashp->BSIZE >> 2; /* divide by 4 */
590 for (i = 0; i < max; i++)
591 M_32_SWAP(((int *)pbuf)[i]);
592 } else {
593 uint16_t *bp = (uint16_t *)(void *)pbuf;
594 max = bp[0] + 2;
595 for (i = 0; i <= max; i++)
596 M_16_SWAP(bp[i]);
597 }
598 p = pbuf;
599 }
600 if (is_bucket)
601 page = BUCKET_TO_PAGE(bucket);
602 else
603 page = OADDR_TO_PAGE(bucket);
604 if ((wsize = pwrite(fd, p, size, (off_t)page << hashp->BSHIFT)) == -1)
605 /* Errno is set */
606 return (-1);
607 if (wsize != size) {
608 errno = EFTYPE;
609 return (-1);
610 }
611 return (0);
612 }
613
614 #define BYTE_MASK ((1 << INT_BYTE_SHIFT) -1)
615 /*
616 * Initialize a new bitmap page. Bitmap pages are left in memory
617 * once they are read in.
618 */
619 int
__ibitmap(HTAB * hashp,int pnum,int nbits,int ndx)620 __ibitmap(HTAB *hashp, int pnum, int nbits, int ndx)
621 {
622 u_int32_t *ip;
623 int clearbytes, clearints;
624
625 if ((ip = (u_int32_t *)malloc(hashp->BSIZE)) == NULL)
626 return (1);
627 hashp->nmaps++;
628 clearints = ((nbits - 1) >> INT_BYTE_SHIFT) + 1;
629 clearbytes = clearints << INT_TO_BYTE;
630 (void)memset((char *)ip, 0, clearbytes);
631 (void)memset(((char *)ip) + clearbytes, 0xFF,
632 hashp->BSIZE - clearbytes);
633 ip[clearints - 1] = ALL_SET << (nbits & BYTE_MASK);
634 SETBIT(ip, 0);
635 hashp->BITMAPS[ndx] = (u_int16_t)pnum;
636 hashp->mapp[ndx] = ip;
637 return (0);
638 }
639
640 static u_int32_t
first_free(u_int32_t map)641 first_free(u_int32_t map)
642 {
643 u_int32_t i, mask;
644
645 mask = 0x1;
646 for (i = 0; i < BITS_PER_MAP; i++) {
647 if (!(mask & map))
648 return (i);
649 mask = mask << 1;
650 }
651 return (i);
652 }
653
654 static u_int16_t
overflow_page(HTAB * hashp)655 overflow_page(HTAB *hashp)
656 {
657 u_int32_t *freep;
658 int max_free, offset, splitnum;
659 u_int16_t addr;
660 int bit, first_page, free_bit, free_page, i, in_use_bits, j;
661 #ifdef DEBUG2
662 int tmp1, tmp2;
663 #endif
664 splitnum = hashp->OVFL_POINT;
665 max_free = hashp->SPARES[splitnum];
666
667 free_page = (max_free - 1) >> (hashp->BSHIFT + BYTE_SHIFT);
668 free_bit = (max_free - 1) & ((hashp->BSIZE << BYTE_SHIFT) - 1);
669
670 /* Look through all the free maps to find the first free block */
671 first_page = hashp->LAST_FREED >>(hashp->BSHIFT + BYTE_SHIFT);
672 for ( i = first_page; i <= free_page; i++ ) {
673 if (!(freep = (u_int32_t *)hashp->mapp[i]) &&
674 !(freep = fetch_bitmap(hashp, i)))
675 return (0);
676 if (i == free_page)
677 in_use_bits = free_bit;
678 else
679 in_use_bits = (hashp->BSIZE << BYTE_SHIFT) - 1;
680
681 if (i == first_page) {
682 bit = hashp->LAST_FREED &
683 ((hashp->BSIZE << BYTE_SHIFT) - 1);
684 j = bit / BITS_PER_MAP;
685 bit = rounddown2(bit, BITS_PER_MAP);
686 } else {
687 bit = 0;
688 j = 0;
689 }
690 for (; bit <= in_use_bits; j++, bit += BITS_PER_MAP)
691 if (freep[j] != ALL_SET)
692 goto found;
693 }
694
695 /* No Free Page Found */
696 hashp->LAST_FREED = hashp->SPARES[splitnum];
697 hashp->SPARES[splitnum]++;
698 offset = hashp->SPARES[splitnum] -
699 (splitnum ? hashp->SPARES[splitnum - 1] : 0);
700
701 #define OVMSG "HASH: Out of overflow pages. Increase page size\n"
702 if (offset > SPLITMASK) {
703 if (++splitnum >= NCACHED) {
704 (void)_write(STDERR_FILENO, OVMSG, sizeof(OVMSG) - 1);
705 errno = EFBIG;
706 return (0);
707 }
708 hashp->OVFL_POINT = splitnum;
709 hashp->SPARES[splitnum] = hashp->SPARES[splitnum-1];
710 hashp->SPARES[splitnum-1]--;
711 offset = 1;
712 }
713
714 /* Check if we need to allocate a new bitmap page */
715 if (free_bit == (hashp->BSIZE << BYTE_SHIFT) - 1) {
716 free_page++;
717 if (free_page >= NCACHED) {
718 (void)_write(STDERR_FILENO, OVMSG, sizeof(OVMSG) - 1);
719 errno = EFBIG;
720 return (0);
721 }
722 /*
723 * This is tricky. The 1 indicates that you want the new page
724 * allocated with 1 clear bit. Actually, you are going to
725 * allocate 2 pages from this map. The first is going to be
726 * the map page, the second is the overflow page we were
727 * looking for. The init_bitmap routine automatically, sets
728 * the first bit of itself to indicate that the bitmap itself
729 * is in use. We would explicitly set the second bit, but
730 * don't have to if we tell init_bitmap not to leave it clear
731 * in the first place.
732 */
733 if (__ibitmap(hashp,
734 (int)OADDR_OF(splitnum, offset), 1, free_page))
735 return (0);
736 hashp->SPARES[splitnum]++;
737 #ifdef DEBUG2
738 free_bit = 2;
739 #endif
740 offset++;
741 if (offset > SPLITMASK) {
742 if (++splitnum >= NCACHED) {
743 (void)_write(STDERR_FILENO, OVMSG,
744 sizeof(OVMSG) - 1);
745 errno = EFBIG;
746 return (0);
747 }
748 hashp->OVFL_POINT = splitnum;
749 hashp->SPARES[splitnum] = hashp->SPARES[splitnum-1];
750 hashp->SPARES[splitnum-1]--;
751 offset = 0;
752 }
753 } else {
754 /*
755 * Free_bit addresses the last used bit. Bump it to address
756 * the first available bit.
757 */
758 free_bit++;
759 SETBIT(freep, free_bit);
760 }
761
762 /* Calculate address of the new overflow page */
763 addr = OADDR_OF(splitnum, offset);
764 #ifdef DEBUG2
765 (void)fprintf(stderr, "OVERFLOW_PAGE: ADDR: %d BIT: %d PAGE %d\n",
766 addr, free_bit, free_page);
767 #endif
768 return (addr);
769
770 found:
771 bit = bit + first_free(freep[j]);
772 SETBIT(freep, bit);
773 #ifdef DEBUG2
774 tmp1 = bit;
775 tmp2 = i;
776 #endif
777 /*
778 * Bits are addressed starting with 0, but overflow pages are addressed
779 * beginning at 1. Bit is a bit addressnumber, so we need to increment
780 * it to convert it to a page number.
781 */
782 bit = 1 + bit + (i * (hashp->BSIZE << BYTE_SHIFT));
783 if (bit >= hashp->LAST_FREED)
784 hashp->LAST_FREED = bit - 1;
785
786 /* Calculate the split number for this page */
787 for (i = 0; (i < splitnum) && (bit > hashp->SPARES[i]); i++);
788 offset = (i ? bit - hashp->SPARES[i - 1] : bit);
789 if (offset >= SPLITMASK) {
790 (void)_write(STDERR_FILENO, OVMSG, sizeof(OVMSG) - 1);
791 errno = EFBIG;
792 return (0); /* Out of overflow pages */
793 }
794 addr = OADDR_OF(i, offset);
795 #ifdef DEBUG2
796 (void)fprintf(stderr, "OVERFLOW_PAGE: ADDR: %d BIT: %d PAGE %d\n",
797 addr, tmp1, tmp2);
798 #endif
799
800 /* Allocate and return the overflow page */
801 return (addr);
802 }
803
804 /*
805 * Mark this overflow page as free.
806 */
807 void
__free_ovflpage(HTAB * hashp,BUFHEAD * obufp)808 __free_ovflpage(HTAB *hashp, BUFHEAD *obufp)
809 {
810 u_int16_t addr;
811 u_int32_t *freep;
812 int bit_address, free_page, free_bit;
813 u_int16_t ndx;
814
815 addr = obufp->addr;
816 #ifdef DEBUG1
817 (void)fprintf(stderr, "Freeing %d\n", addr);
818 #endif
819 ndx = (((u_int16_t)addr) >> SPLITSHIFT);
820 bit_address =
821 (ndx ? hashp->SPARES[ndx - 1] : 0) + (addr & SPLITMASK) - 1;
822 if (bit_address < hashp->LAST_FREED)
823 hashp->LAST_FREED = bit_address;
824 free_page = (bit_address >> (hashp->BSHIFT + BYTE_SHIFT));
825 free_bit = bit_address & ((hashp->BSIZE << BYTE_SHIFT) - 1);
826
827 if (!(freep = hashp->mapp[free_page]))
828 freep = fetch_bitmap(hashp, free_page);
829 #ifdef DEBUG
830 /*
831 * This had better never happen. It means we tried to read a bitmap
832 * that has already had overflow pages allocated off it, and we
833 * failed to read it from the file.
834 */
835 if (!freep)
836 assert(0);
837 #endif
838 CLRBIT(freep, free_bit);
839 #ifdef DEBUG2
840 (void)fprintf(stderr, "FREE_OVFLPAGE: ADDR: %d BIT: %d PAGE %d\n",
841 obufp->addr, free_bit, free_page);
842 #endif
843 __reclaim_buf(hashp, obufp);
844 }
845
846 /*
847 * Returns:
848 * 0 success
849 * -1 failure
850 */
851 static int
open_temp(HTAB * hashp)852 open_temp(HTAB *hashp)
853 {
854 sigset_t set, oset;
855 int len;
856 char *envtmp = NULL;
857 char path[MAXPATHLEN];
858
859 if (issetugid() == 0)
860 envtmp = getenv("TMPDIR");
861 len = snprintf(path,
862 sizeof(path), "%s/_hash.XXXXXX", envtmp ? envtmp : "/tmp");
863 if (len < 0 || len >= (int)sizeof(path)) {
864 errno = ENAMETOOLONG;
865 return (-1);
866 }
867
868 /* Block signals; make sure file goes away at process exit. */
869 (void)sigfillset(&set);
870 (void)__libc_sigprocmask(SIG_BLOCK, &set, &oset);
871 if ((hashp->fp = mkostemp(path, O_CLOEXEC)) != -1)
872 (void)unlink(path);
873 (void)__libc_sigprocmask(SIG_SETMASK, &oset, (sigset_t *)NULL);
874 return (hashp->fp != -1 ? 0 : -1);
875 }
876
877 /*
878 * We have to know that the key will fit, but the last entry on the page is
879 * an overflow pair, so we need to shift things.
880 */
881 static void
squeeze_key(u_int16_t * sp,const DBT * key,const DBT * val)882 squeeze_key(u_int16_t *sp, const DBT *key, const DBT *val)
883 {
884 char *p;
885 u_int16_t free_space, n, off, pageno;
886
887 p = (char *)sp;
888 n = sp[0];
889 free_space = FREESPACE(sp);
890 off = OFFSET(sp);
891
892 pageno = sp[n - 1];
893 off -= key->size;
894 sp[n - 1] = off;
895 memmove(p + off, key->data, key->size);
896 off -= val->size;
897 sp[n] = off;
898 memmove(p + off, val->data, val->size);
899 sp[0] = n + 2;
900 sp[n + 1] = pageno;
901 sp[n + 2] = OVFLPAGE;
902 FREESPACE(sp) = free_space - PAIRSIZE(key, val);
903 OFFSET(sp) = off;
904 }
905
906 static u_int32_t *
fetch_bitmap(HTAB * hashp,int ndx)907 fetch_bitmap(HTAB *hashp, int ndx)
908 {
909 if (ndx >= hashp->nmaps)
910 return (NULL);
911 if ((hashp->mapp[ndx] = (u_int32_t *)malloc(hashp->BSIZE)) == NULL)
912 return (NULL);
913 if (__get_page(hashp,
914 (char *)hashp->mapp[ndx], hashp->BITMAPS[ndx], 0, 1, 1)) {
915 free(hashp->mapp[ndx]);
916 return (NULL);
917 }
918 return (hashp->mapp[ndx]);
919 }
920
921 #ifdef DEBUG4
922 int
print_chain(int addr)923 print_chain(int addr)
924 {
925 BUFHEAD *bufp;
926 short *bp, oaddr;
927
928 (void)fprintf(stderr, "%d ", addr);
929 bufp = __get_buf(hashp, addr, NULL, 0);
930 bp = (short *)bufp->page;
931 while (bp[0] && ((bp[bp[0]] == OVFLPAGE) ||
932 ((bp[0] > 2) && bp[2] < REAL_KEY))) {
933 oaddr = bp[bp[0] - 1];
934 (void)fprintf(stderr, "%d ", (int)oaddr);
935 bufp = __get_buf(hashp, (int)oaddr, bufp, 0);
936 bp = (short *)bufp->page;
937 }
938 (void)fprintf(stderr, "\n");
939 }
940 #endif
941