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_bigkey.c 8.3 (Berkeley) 5/31/94";
37 #endif /* LIBC_SCCS and not lint */
38 #include <sys/cdefs.h>
39 __FBSDID("$FreeBSD$");
40
41 /*
42 * PACKAGE: hash
43 * DESCRIPTION:
44 * Big key/data handling for the hashing package.
45 *
46 * ROUTINES:
47 * External
48 * __big_keydata
49 * __big_split
50 * __big_insert
51 * __big_return
52 * __big_delete
53 * __find_last_page
54 * Internal
55 * collect_key
56 * collect_data
57 */
58
59 #include <sys/param.h>
60
61 #include <errno.h>
62 #include <stdio.h>
63 #include <stdlib.h>
64 #include <string.h>
65
66 #ifdef DEBUG
67 #include <assert.h>
68 #endif
69
70 #include <db.h>
71 #include "hash.h"
72 #include "page.h"
73 #include "extern.h"
74
75 static int collect_key(HTAB *, BUFHEAD *, int, DBT *, int);
76 static int collect_data(HTAB *, BUFHEAD *, int, int);
77
78 /*
79 * Big_insert
80 *
81 * You need to do an insert and the key/data pair is too big
82 *
83 * Returns:
84 * 0 ==> OK
85 *-1 ==> ERROR
86 */
87 int
__big_insert(HTAB * hashp,BUFHEAD * bufp,const DBT * key,const DBT * val)88 __big_insert(HTAB *hashp, BUFHEAD *bufp, const DBT *key, const DBT *val)
89 {
90 u_int16_t *p;
91 int key_size, n;
92 unsigned int val_size;
93 u_int16_t space, move_bytes, off;
94 char *cp, *key_data, *val_data;
95
96 cp = bufp->page; /* Character pointer of p. */
97 p = (u_int16_t *)cp;
98
99 key_data = (char *)key->data;
100 key_size = key->size;
101 val_data = (char *)val->data;
102 val_size = val->size;
103
104 /* First move the Key */
105 for (space = FREESPACE(p) - BIGOVERHEAD; key_size;
106 space = FREESPACE(p) - BIGOVERHEAD) {
107 move_bytes = MIN(space, key_size);
108 off = OFFSET(p) - move_bytes;
109 memmove(cp + off, key_data, move_bytes);
110 key_size -= move_bytes;
111 key_data += move_bytes;
112 n = p[0];
113 p[++n] = off;
114 p[0] = ++n;
115 FREESPACE(p) = off - PAGE_META(n);
116 OFFSET(p) = off;
117 p[n] = PARTIAL_KEY;
118 bufp = __add_ovflpage(hashp, bufp);
119 if (!bufp)
120 return (-1);
121 n = p[0];
122 if (!key_size) {
123 space = FREESPACE(p);
124 if (space) {
125 move_bytes = MIN(space, val_size);
126 /*
127 * If the data would fit exactly in the
128 * remaining space, we must overflow it to the
129 * next page; otherwise the invariant that the
130 * data must end on a page with FREESPACE
131 * non-zero would fail.
132 */
133 if (space == val_size && val_size == val->size)
134 goto toolarge;
135 off = OFFSET(p) - move_bytes;
136 memmove(cp + off, val_data, move_bytes);
137 val_data += move_bytes;
138 val_size -= move_bytes;
139 p[n] = off;
140 p[n - 2] = FULL_KEY_DATA;
141 FREESPACE(p) = FREESPACE(p) - move_bytes;
142 OFFSET(p) = off;
143 } else {
144 toolarge:
145 p[n - 2] = FULL_KEY;
146 }
147 }
148 p = (u_int16_t *)bufp->page;
149 cp = bufp->page;
150 bufp->flags |= BUF_MOD;
151 }
152
153 /* Now move the data */
154 for (space = FREESPACE(p) - BIGOVERHEAD; val_size;
155 space = FREESPACE(p) - BIGOVERHEAD) {
156 move_bytes = MIN(space, val_size);
157 /*
158 * Here's the hack to make sure that if the data ends on the
159 * same page as the key ends, FREESPACE is at least one.
160 */
161 if (space == val_size && val_size == val->size)
162 move_bytes--;
163 off = OFFSET(p) - move_bytes;
164 memmove(cp + off, val_data, move_bytes);
165 val_size -= move_bytes;
166 val_data += move_bytes;
167 n = p[0];
168 p[++n] = off;
169 p[0] = ++n;
170 FREESPACE(p) = off - PAGE_META(n);
171 OFFSET(p) = off;
172 if (val_size) {
173 p[n] = FULL_KEY;
174 bufp = __add_ovflpage(hashp, bufp);
175 if (!bufp)
176 return (-1);
177 cp = bufp->page;
178 p = (u_int16_t *)cp;
179 } else
180 p[n] = FULL_KEY_DATA;
181 bufp->flags |= BUF_MOD;
182 }
183 return (0);
184 }
185
186 /*
187 * Called when bufp's page contains a partial key (index should be 1)
188 *
189 * All pages in the big key/data pair except bufp are freed. We cannot
190 * free bufp because the page pointing to it is lost and we can't get rid
191 * of its pointer.
192 *
193 * Returns:
194 * 0 => OK
195 *-1 => ERROR
196 */
197 int
__big_delete(HTAB * hashp,BUFHEAD * bufp)198 __big_delete(HTAB *hashp, BUFHEAD *bufp)
199 {
200 BUFHEAD *last_bfp, *rbufp;
201 u_int16_t *bp, pageno;
202 int key_done, n;
203
204 rbufp = bufp;
205 last_bfp = NULL;
206 bp = (u_int16_t *)bufp->page;
207 pageno = 0;
208 key_done = 0;
209
210 while (!key_done || (bp[2] != FULL_KEY_DATA)) {
211 if (bp[2] == FULL_KEY || bp[2] == FULL_KEY_DATA)
212 key_done = 1;
213
214 /*
215 * If there is freespace left on a FULL_KEY_DATA page, then
216 * the data is short and fits entirely on this page, and this
217 * is the last page.
218 */
219 if (bp[2] == FULL_KEY_DATA && FREESPACE(bp))
220 break;
221 pageno = bp[bp[0] - 1];
222 rbufp->flags |= BUF_MOD;
223 rbufp = __get_buf(hashp, pageno, rbufp, 0);
224 if (last_bfp)
225 __free_ovflpage(hashp, last_bfp);
226 last_bfp = rbufp;
227 if (!rbufp)
228 return (-1); /* Error. */
229 bp = (u_int16_t *)rbufp->page;
230 }
231
232 /*
233 * If we get here then rbufp points to the last page of the big
234 * key/data pair. Bufp points to the first one -- it should now be
235 * empty pointing to the next page after this pair. Can't free it
236 * because we don't have the page pointing to it.
237 */
238
239 /* This is information from the last page of the pair. */
240 n = bp[0];
241 pageno = bp[n - 1];
242
243 /* Now, bp is the first page of the pair. */
244 bp = (u_int16_t *)bufp->page;
245 if (n > 2) {
246 /* There is an overflow page. */
247 bp[1] = pageno;
248 bp[2] = OVFLPAGE;
249 bufp->ovfl = rbufp->ovfl;
250 } else
251 /* This is the last page. */
252 bufp->ovfl = NULL;
253 n -= 2;
254 bp[0] = n;
255 FREESPACE(bp) = hashp->BSIZE - PAGE_META(n);
256 OFFSET(bp) = hashp->BSIZE;
257
258 bufp->flags |= BUF_MOD;
259 if (rbufp)
260 __free_ovflpage(hashp, rbufp);
261 if (last_bfp && last_bfp != rbufp)
262 __free_ovflpage(hashp, last_bfp);
263
264 hashp->NKEYS--;
265 return (0);
266 }
267 /*
268 * Returns:
269 * 0 = key not found
270 * -1 = get next overflow page
271 * -2 means key not found and this is big key/data
272 * -3 error
273 */
274 int
__find_bigpair(HTAB * hashp,BUFHEAD * bufp,int ndx,char * key,int size)275 __find_bigpair(HTAB *hashp, BUFHEAD *bufp, int ndx, char *key, int size)
276 {
277 u_int16_t *bp;
278 char *p;
279 int ksize;
280 u_int16_t bytes;
281 char *kkey;
282
283 bp = (u_int16_t *)bufp->page;
284 p = bufp->page;
285 ksize = size;
286 kkey = key;
287
288 for (bytes = hashp->BSIZE - bp[ndx];
289 bytes <= size && bp[ndx + 1] == PARTIAL_KEY;
290 bytes = hashp->BSIZE - bp[ndx]) {
291 if (memcmp(p + bp[ndx], kkey, bytes))
292 return (-2);
293 kkey += bytes;
294 ksize -= bytes;
295 bufp = __get_buf(hashp, bp[ndx + 2], bufp, 0);
296 if (!bufp)
297 return (-3);
298 p = bufp->page;
299 bp = (u_int16_t *)p;
300 ndx = 1;
301 }
302
303 if (bytes != ksize || memcmp(p + bp[ndx], kkey, bytes)) {
304 #ifdef HASH_STATISTICS
305 ++hash_collisions;
306 #endif
307 return (-2);
308 } else
309 return (ndx);
310 }
311
312 /*
313 * Given the buffer pointer of the first overflow page of a big pair,
314 * find the end of the big pair
315 *
316 * This will set bpp to the buffer header of the last page of the big pair.
317 * It will return the pageno of the overflow page following the last page
318 * of the pair; 0 if there isn't any (i.e. big pair is the last key in the
319 * bucket)
320 */
321 u_int16_t
__find_last_page(HTAB * hashp,BUFHEAD ** bpp)322 __find_last_page(HTAB *hashp, BUFHEAD **bpp)
323 {
324 BUFHEAD *bufp;
325 u_int16_t *bp, pageno;
326 int n;
327
328 bufp = *bpp;
329 bp = (u_int16_t *)bufp->page;
330 for (;;) {
331 n = bp[0];
332
333 /*
334 * This is the last page if: the tag is FULL_KEY_DATA and
335 * either only 2 entries OVFLPAGE marker is explicit there
336 * is freespace on the page.
337 */
338 if (bp[2] == FULL_KEY_DATA &&
339 ((n == 2) || (bp[n] == OVFLPAGE) || (FREESPACE(bp))))
340 break;
341
342 pageno = bp[n - 1];
343 bufp = __get_buf(hashp, pageno, bufp, 0);
344 if (!bufp)
345 return (0); /* Need to indicate an error! */
346 bp = (u_int16_t *)bufp->page;
347 }
348
349 *bpp = bufp;
350 if (bp[0] > 2)
351 return (bp[3]);
352 else
353 return (0);
354 }
355
356 /*
357 * Return the data for the key/data pair that begins on this page at this
358 * index (index should always be 1).
359 */
360 int
__big_return(HTAB * hashp,BUFHEAD * bufp,int ndx,DBT * val,int set_current)361 __big_return(HTAB *hashp, BUFHEAD *bufp, int ndx, DBT *val, int set_current)
362 {
363 BUFHEAD *save_p;
364 u_int16_t *bp, len, off, save_addr;
365 char *tp;
366
367 bp = (u_int16_t *)bufp->page;
368 while (bp[ndx + 1] == PARTIAL_KEY) {
369 bufp = __get_buf(hashp, bp[bp[0] - 1], bufp, 0);
370 if (!bufp)
371 return (-1);
372 bp = (u_int16_t *)bufp->page;
373 ndx = 1;
374 }
375
376 if (bp[ndx + 1] == FULL_KEY) {
377 bufp = __get_buf(hashp, bp[bp[0] - 1], bufp, 0);
378 if (!bufp)
379 return (-1);
380 bp = (u_int16_t *)bufp->page;
381 save_p = bufp;
382 save_addr = save_p->addr;
383 off = bp[1];
384 len = 0;
385 } else
386 if (!FREESPACE(bp)) {
387 /*
388 * This is a hack. We can't distinguish between
389 * FULL_KEY_DATA that contains complete data or
390 * incomplete data, so we require that if the data
391 * is complete, there is at least 1 byte of free
392 * space left.
393 */
394 off = bp[bp[0]];
395 len = bp[1] - off;
396 save_p = bufp;
397 save_addr = bufp->addr;
398 bufp = __get_buf(hashp, bp[bp[0] - 1], bufp, 0);
399 if (!bufp)
400 return (-1);
401 bp = (u_int16_t *)bufp->page;
402 } else {
403 /* The data is all on one page. */
404 tp = (char *)bp;
405 off = bp[bp[0]];
406 val->data = (u_char *)tp + off;
407 val->size = bp[1] - off;
408 if (set_current) {
409 if (bp[0] == 2) { /* No more buckets in
410 * chain */
411 hashp->cpage = NULL;
412 hashp->cbucket++;
413 hashp->cndx = 1;
414 } else {
415 hashp->cpage = __get_buf(hashp,
416 bp[bp[0] - 1], bufp, 0);
417 if (!hashp->cpage)
418 return (-1);
419 hashp->cndx = 1;
420 if (!((u_int16_t *)
421 hashp->cpage->page)[0]) {
422 hashp->cbucket++;
423 hashp->cpage = NULL;
424 }
425 }
426 }
427 return (0);
428 }
429
430 val->size = (size_t)collect_data(hashp, bufp, (int)len, set_current);
431 if (val->size == (size_t)-1)
432 return (-1);
433 if (save_p->addr != save_addr) {
434 /* We are pretty short on buffers. */
435 errno = EINVAL; /* OUT OF BUFFERS */
436 return (-1);
437 }
438 memmove(hashp->tmp_buf, (save_p->page) + off, len);
439 val->data = (u_char *)hashp->tmp_buf;
440 return (0);
441 }
442 /*
443 * Count how big the total datasize is by recursing through the pages. Then
444 * allocate a buffer and copy the data as you recurse up.
445 */
446 static int
collect_data(HTAB * hashp,BUFHEAD * bufp,int len,int set)447 collect_data(HTAB *hashp, BUFHEAD *bufp, int len, int set)
448 {
449 u_int16_t *bp;
450 char *p;
451 BUFHEAD *xbp;
452 u_int16_t save_addr;
453 int mylen, totlen;
454
455 p = bufp->page;
456 bp = (u_int16_t *)p;
457 mylen = hashp->BSIZE - bp[1];
458 save_addr = bufp->addr;
459
460 if (bp[2] == FULL_KEY_DATA) { /* End of Data */
461 totlen = len + mylen;
462 if (hashp->tmp_buf)
463 free(hashp->tmp_buf);
464 if ((hashp->tmp_buf = (char *)malloc(totlen)) == NULL)
465 return (-1);
466 if (set) {
467 hashp->cndx = 1;
468 if (bp[0] == 2) { /* No more buckets in chain */
469 hashp->cpage = NULL;
470 hashp->cbucket++;
471 } else {
472 hashp->cpage =
473 __get_buf(hashp, bp[bp[0] - 1], bufp, 0);
474 if (!hashp->cpage)
475 return (-1);
476 else if (!((u_int16_t *)hashp->cpage->page)[0]) {
477 hashp->cbucket++;
478 hashp->cpage = NULL;
479 }
480 }
481 }
482 } else {
483 xbp = __get_buf(hashp, bp[bp[0] - 1], bufp, 0);
484 if (!xbp || ((totlen =
485 collect_data(hashp, xbp, len + mylen, set)) < 1))
486 return (-1);
487 }
488 if (bufp->addr != save_addr) {
489 errno = EINVAL; /* Out of buffers. */
490 return (-1);
491 }
492 memmove(&hashp->tmp_buf[len], (bufp->page) + bp[1], mylen);
493 return (totlen);
494 }
495
496 /*
497 * Fill in the key and data for this big pair.
498 */
499 int
__big_keydata(HTAB * hashp,BUFHEAD * bufp,DBT * key,DBT * val,int set)500 __big_keydata(HTAB *hashp, BUFHEAD *bufp, DBT *key, DBT *val, int set)
501 {
502 key->size = (size_t)collect_key(hashp, bufp, 0, val, set);
503 if (key->size == (size_t)-1)
504 return (-1);
505 key->data = (u_char *)hashp->tmp_key;
506 return (0);
507 }
508
509 /*
510 * Count how big the total key size is by recursing through the pages. Then
511 * collect the data, allocate a buffer and copy the key as you recurse up.
512 */
513 static int
collect_key(HTAB * hashp,BUFHEAD * bufp,int len,DBT * val,int set)514 collect_key(HTAB *hashp, BUFHEAD *bufp, int len, DBT *val, int set)
515 {
516 BUFHEAD *xbp;
517 char *p;
518 int mylen, totlen;
519 u_int16_t *bp, save_addr;
520
521 p = bufp->page;
522 bp = (u_int16_t *)p;
523 mylen = hashp->BSIZE - bp[1];
524
525 save_addr = bufp->addr;
526 totlen = len + mylen;
527 if (bp[2] == FULL_KEY || bp[2] == FULL_KEY_DATA) { /* End of Key. */
528 if (hashp->tmp_key != NULL)
529 free(hashp->tmp_key);
530 if ((hashp->tmp_key = (char *)malloc(totlen)) == NULL)
531 return (-1);
532 if (__big_return(hashp, bufp, 1, val, set))
533 return (-1);
534 } else {
535 xbp = __get_buf(hashp, bp[bp[0] - 1], bufp, 0);
536 if (!xbp || ((totlen =
537 collect_key(hashp, xbp, totlen, val, set)) < 1))
538 return (-1);
539 }
540 if (bufp->addr != save_addr) {
541 errno = EINVAL; /* MIS -- OUT OF BUFFERS */
542 return (-1);
543 }
544 memmove(&hashp->tmp_key[len], (bufp->page) + bp[1], mylen);
545 return (totlen);
546 }
547
548 /*
549 * Returns:
550 * 0 => OK
551 * -1 => error
552 */
553 int
__big_split(HTAB * hashp,BUFHEAD * op,BUFHEAD * np,BUFHEAD * big_keyp,int addr,u_int32_t obucket,SPLIT_RETURN * ret)554 __big_split(HTAB *hashp,
555 BUFHEAD *op, /* Pointer to where to put keys that go in old bucket */
556 BUFHEAD *np, /* Pointer to new bucket page */
557 BUFHEAD *big_keyp, /* Pointer to first page containing the big key/data */
558 int addr, /* Address of big_keyp */
559 u_int32_t obucket, /* Old Bucket */
560 SPLIT_RETURN *ret)
561 {
562 BUFHEAD *bp, *tmpp;
563 DBT key, val;
564 u_int32_t change;
565 u_int16_t free_space, n, off, *tp;
566
567 bp = big_keyp;
568
569 /* Now figure out where the big key/data goes */
570 if (__big_keydata(hashp, big_keyp, &key, &val, 0))
571 return (-1);
572 change = (__call_hash(hashp, key.data, key.size) != obucket);
573
574 if ( (ret->next_addr = __find_last_page(hashp, &big_keyp)) ) {
575 if (!(ret->nextp =
576 __get_buf(hashp, ret->next_addr, big_keyp, 0)))
577 return (-1);
578 } else
579 ret->nextp = NULL;
580
581 /* Now make one of np/op point to the big key/data pair */
582 #ifdef DEBUG
583 assert(np->ovfl == NULL);
584 #endif
585 if (change)
586 tmpp = np;
587 else
588 tmpp = op;
589
590 tmpp->flags |= BUF_MOD;
591 #ifdef DEBUG1
592 (void)fprintf(stderr,
593 "BIG_SPLIT: %d->ovfl was %d is now %d\n", tmpp->addr,
594 (tmpp->ovfl ? tmpp->ovfl->addr : 0), (bp ? bp->addr : 0));
595 #endif
596 tmpp->ovfl = bp; /* one of op/np point to big_keyp */
597 tp = (u_int16_t *)tmpp->page;
598 #ifdef DEBUG
599 assert(FREESPACE(tp) >= OVFLSIZE);
600 #endif
601 n = tp[0];
602 off = OFFSET(tp);
603 free_space = FREESPACE(tp);
604 tp[++n] = (u_int16_t)addr;
605 tp[++n] = OVFLPAGE;
606 tp[0] = n;
607 OFFSET(tp) = off;
608 FREESPACE(tp) = free_space - OVFLSIZE;
609
610 /*
611 * Finally, set the new and old return values. BIG_KEYP contains a
612 * pointer to the last page of the big key_data pair. Make sure that
613 * big_keyp has no following page (2 elements) or create an empty
614 * following page.
615 */
616
617 ret->newp = np;
618 ret->oldp = op;
619
620 tp = (u_int16_t *)big_keyp->page;
621 big_keyp->flags |= BUF_MOD;
622 if (tp[0] > 2) {
623 /*
624 * There may be either one or two offsets on this page. If
625 * there is one, then the overflow page is linked on normally
626 * and tp[4] is OVFLPAGE. If there are two, tp[4] contains
627 * the second offset and needs to get stuffed in after the
628 * next overflow page is added.
629 */
630 n = tp[4];
631 free_space = FREESPACE(tp);
632 off = OFFSET(tp);
633 tp[0] -= 2;
634 FREESPACE(tp) = free_space + OVFLSIZE;
635 OFFSET(tp) = off;
636 tmpp = __add_ovflpage(hashp, big_keyp);
637 if (!tmpp)
638 return (-1);
639 tp[4] = n;
640 } else
641 tmpp = big_keyp;
642
643 if (change)
644 ret->newp = tmpp;
645 else
646 ret->oldp = tmpp;
647 return (0);
648 }
649