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