Apply FreeBSD-SA-09:07.libc - fix information leak in db(3)
[dragonfly.git] / lib / libc / db / btree / bt_split.c
CommitLineData
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1/*-
2 * Copyright (c) 1990, 1993, 1994
3 * The Regents of the University of California. All rights reserved.
4 *
5 * This code is derived from software contributed to Berkeley by
6 * Mike Olson.
7 *
8 * Redistribution and use in source and binary forms, with or without
9 * modification, are permitted provided that the following conditions
10 * are met:
11 * 1. Redistributions of source code must retain the above copyright
12 * notice, this list of conditions and the following disclaimer.
13 * 2. Redistributions in binary form must reproduce the above copyright
14 * notice, this list of conditions and the following disclaimer in the
15 * documentation and/or other materials provided with the distribution.
cbebfd39 16 * 3. Neither the name of the University nor the names of its contributors
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17 * may be used to endorse or promote products derived from this software
18 * without specific prior written permission.
19 *
20 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
21 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
22 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
23 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
24 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
25 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
26 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
27 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
28 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
29 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
30 * SUCH DAMAGE.
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31 *
32 * @(#)bt_split.c 8.9 (Berkeley) 7/26/94
17d47efc 33 * $DragonFly: src/lib/libc/db/btree/bt_split.c,v 1.8 2005/11/19 20:46:32 swildner Exp $
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34 */
35
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36#include <sys/types.h>
37
38#include <limits.h>
39#include <stdio.h>
40#include <stdlib.h>
41#include <string.h>
42
43#include <db.h>
44#include "btree.h"
45
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46static int bt_broot(BTREE *, PAGE *, PAGE *, PAGE *);
47static PAGE *bt_page(BTREE *, PAGE *, PAGE **, PAGE **, indx_t *, size_t);
48static int bt_preserve(BTREE *, pgno_t);
49static PAGE *bt_psplit(BTREE *, PAGE *, PAGE *, PAGE *, indx_t *, size_t);
50static PAGE *bt_root(BTREE *, PAGE *, PAGE **, PAGE **, indx_t *, size_t);
51static int bt_rroot(BTREE *, PAGE *, PAGE *, PAGE *);
52static recno_t rec_total(PAGE *);
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53
54#ifdef STATISTICS
55u_long bt_rootsplit, bt_split, bt_sortsplit, bt_pfxsaved;
56#endif
57
58/*
59 * __BT_SPLIT -- Split the tree.
60 *
61 * Parameters:
62 * t: tree
63 * sp: page to split
64 * key: key to insert
65 * data: data to insert
66 * flags: BIGKEY/BIGDATA flags
67 * ilen: insert length
68 * skip: index to leave open
69 *
70 * Returns:
71 * RET_ERROR, RET_SUCCESS
72 */
73int
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74__bt_split(BTREE *t, PAGE *sp, const DBT *key, const DBT *data, int flags,
75 size_t ilen, u_int32_t argskip)
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76{
77 BINTERNAL *bi;
78 BLEAF *bl, *tbl;
79 DBT a, b;
80 EPGNO *parent;
81 PAGE *h, *l, *r, *lchild, *rchild;
82 indx_t nxtindex;
83 u_int16_t skip;
84 u_int32_t n, nbytes, nksize;
85 int parentsplit;
86 char *dest;
87
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88 bi = NULL;
89 bl = NULL;
90 nksize = 0;
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91 /*
92 * Split the page into two pages, l and r. The split routines return
93 * a pointer to the page into which the key should be inserted and with
94 * skip set to the offset which should be used. Additionally, l and r
95 * are pinned.
96 */
97 skip = argskip;
98 h = sp->pgno == P_ROOT ?
99 bt_root(t, sp, &l, &r, &skip, ilen) :
100 bt_page(t, sp, &l, &r, &skip, ilen);
101 if (h == NULL)
102 return (RET_ERROR);
103
104 /*
105 * Insert the new key/data pair into the leaf page. (Key inserts
106 * always cause a leaf page to split first.)
107 */
108 h->linp[skip] = h->upper -= ilen;
109 dest = (char *)h + h->upper;
110 if (F_ISSET(t, R_RECNO))
111 WR_RLEAF(dest, data, flags)
112 else
113 WR_BLEAF(dest, key, data, flags)
114
115 /* If the root page was split, make it look right. */
116 if (sp->pgno == P_ROOT &&
117 (F_ISSET(t, R_RECNO) ?
118 bt_rroot(t, sp, l, r) : bt_broot(t, sp, l, r)) == RET_ERROR)
119 goto err2;
120
121 /*
122 * Now we walk the parent page stack -- a LIFO stack of the pages that
123 * were traversed when we searched for the page that split. Each stack
124 * entry is a page number and a page index offset. The offset is for
125 * the page traversed on the search. We've just split a page, so we
126 * have to insert a new key into the parent page.
127 *
128 * If the insert into the parent page causes it to split, may have to
129 * continue splitting all the way up the tree. We stop if the root
130 * splits or the page inserted into didn't have to split to hold the
131 * new key. Some algorithms replace the key for the old page as well
132 * as the new page. We don't, as there's no reason to believe that the
133 * first key on the old page is any better than the key we have, and,
134 * in the case of a key being placed at index 0 causing the split, the
135 * key is unavailable.
136 *
137 * There are a maximum of 5 pages pinned at any time. We keep the left
138 * and right pages pinned while working on the parent. The 5 are the
139 * two children, left parent and right parent (when the parent splits)
140 * and the root page or the overflow key page when calling bt_preserve.
141 * This code must make sure that all pins are released other than the
142 * root page or overflow page which is unlocked elsewhere.
143 */
144 while ((parent = BT_POP(t)) != NULL) {
145 lchild = l;
146 rchild = r;
147
148 /* Get the parent page. */
149 if ((h = mpool_get(t->bt_mp, parent->pgno, 0)) == NULL)
150 goto err2;
151
5aa057b6 152 /*
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153 * The new key goes ONE AFTER the index, because the split
154 * was to the right.
155 */
156 skip = parent->index + 1;
157
158 /*
159 * Calculate the space needed on the parent page.
160 *
161 * Prefix trees: space hack when inserting into BINTERNAL
162 * pages. Retain only what's needed to distinguish between
163 * the new entry and the LAST entry on the page to its left.
164 * If the keys compare equal, retain the entire key. Note,
165 * we don't touch overflow keys, and the entire key must be
166 * retained for the next-to-left most key on the leftmost
167 * page of each level, or the search will fail. Applicable
168 * ONLY to internal pages that have leaf pages as children.
169 * Further reduction of the key between pairs of internal
170 * pages loses too much information.
171 */
172 switch (rchild->flags & P_TYPE) {
173 case P_BINTERNAL:
174 bi = GETBINTERNAL(rchild, 0);
175 nbytes = NBINTERNAL(bi->ksize);
176 break;
177 case P_BLEAF:
178 bl = GETBLEAF(rchild, 0);
179 nbytes = NBINTERNAL(bl->ksize);
180 if (t->bt_pfx && !(bl->flags & P_BIGKEY) &&
181 (h->prevpg != P_INVALID || skip > 1)) {
182 tbl = GETBLEAF(lchild, NEXTINDEX(lchild) - 1);
183 a.size = tbl->ksize;
184 a.data = tbl->bytes;
185 b.size = bl->ksize;
186 b.data = bl->bytes;
187 nksize = t->bt_pfx(&a, &b);
188 n = NBINTERNAL(nksize);
189 if (n < nbytes) {
190#ifdef STATISTICS
191 bt_pfxsaved += nbytes - n;
192#endif
193 nbytes = n;
194 } else
195 nksize = 0;
196 } else
197 nksize = 0;
198 break;
199 case P_RINTERNAL:
200 case P_RLEAF:
201 nbytes = NRINTERNAL;
202 break;
203 default:
204 abort();
205 }
206
207 /* Split the parent page if necessary or shift the indices. */
208 if (h->upper - h->lower < nbytes + sizeof(indx_t)) {
209 sp = h;
210 h = h->pgno == P_ROOT ?
211 bt_root(t, h, &l, &r, &skip, nbytes) :
212 bt_page(t, h, &l, &r, &skip, nbytes);
213 if (h == NULL)
214 goto err1;
215 parentsplit = 1;
216 } else {
217 if (skip < (nxtindex = NEXTINDEX(h)))
218 memmove(h->linp + skip + 1, h->linp + skip,
219 (nxtindex - skip) * sizeof(indx_t));
220 h->lower += sizeof(indx_t);
221 parentsplit = 0;
222 }
223
224 /* Insert the key into the parent page. */
225 switch (rchild->flags & P_TYPE) {
226 case P_BINTERNAL:
227 h->linp[skip] = h->upper -= nbytes;
228 dest = (char *)h + h->linp[skip];
229 memmove(dest, bi, nbytes);
230 ((BINTERNAL *)dest)->pgno = rchild->pgno;
231 break;
232 case P_BLEAF:
233 h->linp[skip] = h->upper -= nbytes;
234 dest = (char *)h + h->linp[skip];
235 WR_BINTERNAL(dest, nksize ? nksize : bl->ksize,
236 rchild->pgno, bl->flags & P_BIGKEY);
237 memmove(dest, bl->bytes, nksize ? nksize : bl->ksize);
238 if (bl->flags & P_BIGKEY &&
239 bt_preserve(t, *(pgno_t *)bl->bytes) == RET_ERROR)
240 goto err1;
241 break;
242 case P_RINTERNAL:
243 /*
244 * Update the left page count. If split
245 * added at index 0, fix the correct page.
246 */
247 if (skip > 0)
248 dest = (char *)h + h->linp[skip - 1];
249 else
250 dest = (char *)l + l->linp[NEXTINDEX(l) - 1];
251 ((RINTERNAL *)dest)->nrecs = rec_total(lchild);
252 ((RINTERNAL *)dest)->pgno = lchild->pgno;
253
254 /* Update the right page count. */
255 h->linp[skip] = h->upper -= nbytes;
256 dest = (char *)h + h->linp[skip];
257 ((RINTERNAL *)dest)->nrecs = rec_total(rchild);
258 ((RINTERNAL *)dest)->pgno = rchild->pgno;
259 break;
260 case P_RLEAF:
261 /*
262 * Update the left page count. If split
263 * added at index 0, fix the correct page.
264 */
265 if (skip > 0)
266 dest = (char *)h + h->linp[skip - 1];
267 else
268 dest = (char *)l + l->linp[NEXTINDEX(l) - 1];
269 ((RINTERNAL *)dest)->nrecs = NEXTINDEX(lchild);
270 ((RINTERNAL *)dest)->pgno = lchild->pgno;
271
272 /* Update the right page count. */
273 h->linp[skip] = h->upper -= nbytes;
274 dest = (char *)h + h->linp[skip];
275 ((RINTERNAL *)dest)->nrecs = NEXTINDEX(rchild);
276 ((RINTERNAL *)dest)->pgno = rchild->pgno;
277 break;
278 default:
279 abort();
280 }
281
282 /* Unpin the held pages. */
283 if (!parentsplit) {
284 mpool_put(t->bt_mp, h, MPOOL_DIRTY);
285 break;
286 }
287
288 /* If the root page was split, make it look right. */
289 if (sp->pgno == P_ROOT &&
290 (F_ISSET(t, R_RECNO) ?
291 bt_rroot(t, sp, l, r) : bt_broot(t, sp, l, r)) == RET_ERROR)
292 goto err1;
293
294 mpool_put(t->bt_mp, lchild, MPOOL_DIRTY);
295 mpool_put(t->bt_mp, rchild, MPOOL_DIRTY);
296 }
297
298 /* Unpin the held pages. */
299 mpool_put(t->bt_mp, l, MPOOL_DIRTY);
300 mpool_put(t->bt_mp, r, MPOOL_DIRTY);
301
302 /* Clear any pages left on the stack. */
303 return (RET_SUCCESS);
304
305 /*
306 * If something fails in the above loop we were already walking back
307 * up the tree and the tree is now inconsistent. Nothing much we can
308 * do about it but release any memory we're holding.
309 */
310err1: mpool_put(t->bt_mp, lchild, MPOOL_DIRTY);
311 mpool_put(t->bt_mp, rchild, MPOOL_DIRTY);
312
313err2: mpool_put(t->bt_mp, l, 0);
314 mpool_put(t->bt_mp, r, 0);
315 __dbpanic(t->bt_dbp);
316 return (RET_ERROR);
317}
318
319/*
320 * BT_PAGE -- Split a non-root page of a btree.
321 *
322 * Parameters:
323 * t: tree
324 * h: root page
325 * lp: pointer to left page pointer
326 * rp: pointer to right page pointer
327 * skip: pointer to index to leave open
328 * ilen: insert length
329 *
330 * Returns:
331 * Pointer to page in which to insert or NULL on error.
332 */
333static PAGE *
c9fbf0d3 334bt_page(BTREE *t, PAGE *h, PAGE **lp, PAGE **rp, indx_t *skip, size_t ilen)
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335{
336 PAGE *l, *r, *tp;
337 pgno_t npg;
338
339#ifdef STATISTICS
340 ++bt_split;
341#endif
342 /* Put the new right page for the split into place. */
343 if ((r = __bt_new(t, &npg)) == NULL)
344 return (NULL);
345 r->pgno = npg;
346 r->lower = BTDATAOFF;
347 r->upper = t->bt_psize;
348 r->nextpg = h->nextpg;
349 r->prevpg = h->pgno;
350 r->flags = h->flags & P_TYPE;
351
352 /*
353 * If we're splitting the last page on a level because we're appending
354 * a key to it (skip is NEXTINDEX()), it's likely that the data is
355 * sorted. Adding an empty page on the side of the level is less work
356 * and can push the fill factor much higher than normal. If we're
357 * wrong it's no big deal, we'll just do the split the right way next
358 * time. It may look like it's equally easy to do a similar hack for
359 * reverse sorted data, that is, split the tree left, but it's not.
360 * Don't even try.
361 */
362 if (h->nextpg == P_INVALID && *skip == NEXTINDEX(h)) {
363#ifdef STATISTICS
364 ++bt_sortsplit;
365#endif
366 h->nextpg = r->pgno;
367 r->lower = BTDATAOFF + sizeof(indx_t);
368 *skip = 0;
369 *lp = h;
370 *rp = r;
371 return (r);
372 }
373
374 /* Put the new left page for the split into place. */
7895edcd 375 if ((l = (PAGE *)calloc(1, t->bt_psize)) == NULL) {
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376 mpool_put(t->bt_mp, r, 0);
377 return (NULL);
378 }
379#ifdef PURIFY
380 memset(l, 0xff, t->bt_psize);
381#endif
382 l->pgno = h->pgno;
383 l->nextpg = r->pgno;
384 l->prevpg = h->prevpg;
385 l->lower = BTDATAOFF;
386 l->upper = t->bt_psize;
387 l->flags = h->flags & P_TYPE;
388
389 /* Fix up the previous pointer of the page after the split page. */
390 if (h->nextpg != P_INVALID) {
391 if ((tp = mpool_get(t->bt_mp, h->nextpg, 0)) == NULL) {
392 free(l);
393 /* XXX mpool_free(t->bt_mp, r->pgno); */
394 return (NULL);
395 }
396 tp->prevpg = r->pgno;
397 mpool_put(t->bt_mp, tp, MPOOL_DIRTY);
398 }
399
400 /*
401 * Split right. The key/data pairs aren't sorted in the btree page so
402 * it's simpler to copy the data from the split page onto two new pages
403 * instead of copying half the data to the right page and compacting
404 * the left page in place. Since the left page can't change, we have
405 * to swap the original and the allocated left page after the split.
406 */
407 tp = bt_psplit(t, h, l, r, skip, ilen);
408
409 /* Move the new left page onto the old left page. */
410 memmove(h, l, t->bt_psize);
411 if (tp == l)
412 tp = h;
413 free(l);
414
415 *lp = h;
416 *rp = r;
417 return (tp);
418}
419
420/*
421 * BT_ROOT -- Split the root page of a btree.
422 *
423 * Parameters:
424 * t: tree
425 * h: root page
426 * lp: pointer to left page pointer
427 * rp: pointer to right page pointer
428 * skip: pointer to index to leave open
429 * ilen: insert length
430 *
431 * Returns:
432 * Pointer to page in which to insert or NULL on error.
433 */
434static PAGE *
c9fbf0d3 435bt_root(BTREE *t, PAGE *h, PAGE **lp, PAGE **rp, indx_t *skip, size_t ilen)
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436{
437 PAGE *l, *r, *tp;
438 pgno_t lnpg, rnpg;
439
440#ifdef STATISTICS
441 ++bt_split;
442 ++bt_rootsplit;
443#endif
444 /* Put the new left and right pages for the split into place. */
445 if ((l = __bt_new(t, &lnpg)) == NULL ||
446 (r = __bt_new(t, &rnpg)) == NULL)
447 return (NULL);
448 l->pgno = lnpg;
449 r->pgno = rnpg;
450 l->nextpg = r->pgno;
451 r->prevpg = l->pgno;
452 l->prevpg = r->nextpg = P_INVALID;
453 l->lower = r->lower = BTDATAOFF;
454 l->upper = r->upper = t->bt_psize;
455 l->flags = r->flags = h->flags & P_TYPE;
456
457 /* Split the root page. */
458 tp = bt_psplit(t, h, l, r, skip, ilen);
459
460 *lp = l;
461 *rp = r;
462 return (tp);
463}
464
465/*
466 * BT_RROOT -- Fix up the recno root page after it has been split.
467 *
468 * Parameters:
469 * t: tree
470 * h: root page
471 * l: left page
472 * r: right page
473 *
474 * Returns:
475 * RET_ERROR, RET_SUCCESS
476 */
477static int
c9fbf0d3 478bt_rroot(BTREE *t, PAGE *h, PAGE *l, PAGE *r)
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479{
480 char *dest;
481
482 /* Insert the left and right keys, set the header information. */
483 h->linp[0] = h->upper = t->bt_psize - NRINTERNAL;
484 dest = (char *)h + h->upper;
485 WR_RINTERNAL(dest,
486 l->flags & P_RLEAF ? NEXTINDEX(l) : rec_total(l), l->pgno);
487
488 h->linp[1] = h->upper -= NRINTERNAL;
489 dest = (char *)h + h->upper;
490 WR_RINTERNAL(dest,
491 r->flags & P_RLEAF ? NEXTINDEX(r) : rec_total(r), r->pgno);
492
493 h->lower = BTDATAOFF + 2 * sizeof(indx_t);
494
495 /* Unpin the root page, set to recno internal page. */
496 h->flags &= ~P_TYPE;
497 h->flags |= P_RINTERNAL;
498 mpool_put(t->bt_mp, h, MPOOL_DIRTY);
499
500 return (RET_SUCCESS);
501}
502
503/*
504 * BT_BROOT -- Fix up the btree root page after it has been split.
505 *
506 * Parameters:
507 * t: tree
508 * h: root page
509 * l: left page
510 * r: right page
511 *
512 * Returns:
513 * RET_ERROR, RET_SUCCESS
514 */
515static int
c9fbf0d3 516bt_broot(BTREE *t, PAGE *h, PAGE *l, PAGE *r)
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517{
518 BINTERNAL *bi;
519 BLEAF *bl;
520 u_int32_t nbytes;
521 char *dest;
522
523 /*
524 * If the root page was a leaf page, change it into an internal page.
525 * We copy the key we split on (but not the key's data, in the case of
526 * a leaf page) to the new root page.
527 *
528 * The btree comparison code guarantees that the left-most key on any
529 * level of the tree is never used, so it doesn't need to be filled in.
530 */
531 nbytes = NBINTERNAL(0);
532 h->linp[0] = h->upper = t->bt_psize - nbytes;
533 dest = (char *)h + h->upper;
534 WR_BINTERNAL(dest, 0, l->pgno, 0);
535
536 switch (h->flags & P_TYPE) {
537 case P_BLEAF:
538 bl = GETBLEAF(r, 0);
539 nbytes = NBINTERNAL(bl->ksize);
540 h->linp[1] = h->upper -= nbytes;
541 dest = (char *)h + h->upper;
542 WR_BINTERNAL(dest, bl->ksize, r->pgno, 0);
543 memmove(dest, bl->bytes, bl->ksize);
544
545 /*
546 * If the key is on an overflow page, mark the overflow chain
547 * so it isn't deleted when the leaf copy of the key is deleted.
548 */
549 if (bl->flags & P_BIGKEY &&
550 bt_preserve(t, *(pgno_t *)bl->bytes) == RET_ERROR)
551 return (RET_ERROR);
552 break;
553 case P_BINTERNAL:
554 bi = GETBINTERNAL(r, 0);
555 nbytes = NBINTERNAL(bi->ksize);
556 h->linp[1] = h->upper -= nbytes;
557 dest = (char *)h + h->upper;
558 memmove(dest, bi, nbytes);
559 ((BINTERNAL *)dest)->pgno = r->pgno;
560 break;
561 default:
562 abort();
563 }
564
565 /* There are two keys on the page. */
566 h->lower = BTDATAOFF + 2 * sizeof(indx_t);
567
568 /* Unpin the root page, set to btree internal page. */
569 h->flags &= ~P_TYPE;
570 h->flags |= P_BINTERNAL;
571 mpool_put(t->bt_mp, h, MPOOL_DIRTY);
572
573 return (RET_SUCCESS);
574}
575
576/*
577 * BT_PSPLIT -- Do the real work of splitting the page.
578 *
579 * Parameters:
580 * t: tree
581 * h: page to be split
582 * l: page to put lower half of data
583 * r: page to put upper half of data
584 * pskip: pointer to index to leave open
585 * ilen: insert length
586 *
587 * Returns:
588 * Pointer to page in which to insert.
589 */
590static PAGE *
c9fbf0d3 591bt_psplit(BTREE *t, PAGE *h, PAGE *l, PAGE *r, indx_t *pskip, size_t ilen)
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592{
593 BINTERNAL *bi;
594 BLEAF *bl;
595 CURSOR *c;
596 RLEAF *rl;
597 PAGE *rval;
598 void *src;
599 indx_t full, half, nxt, off, skip, top, used;
600 u_int32_t nbytes;
601 int bigkeycnt, isbigkey;
602
17d47efc 603 src = NULL;
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604 /*
605 * Split the data to the left and right pages. Leave the skip index
606 * open. Additionally, make some effort not to split on an overflow
607 * key. This makes internal page processing faster and can save
608 * space as overflow keys used by internal pages are never deleted.
609 */
610 bigkeycnt = 0;
611 skip = *pskip;
612 full = t->bt_psize - BTDATAOFF;
613 half = full / 2;
614 used = 0;
615 for (nxt = off = 0, top = NEXTINDEX(h); nxt < top; ++off) {
616 if (skip == off) {
617 nbytes = ilen;
618 isbigkey = 0; /* XXX: not really known. */
619 } else
620 switch (h->flags & P_TYPE) {
621 case P_BINTERNAL:
622 src = bi = GETBINTERNAL(h, nxt);
623 nbytes = NBINTERNAL(bi->ksize);
624 isbigkey = bi->flags & P_BIGKEY;
625 break;
626 case P_BLEAF:
627 src = bl = GETBLEAF(h, nxt);
628 nbytes = NBLEAF(bl);
629 isbigkey = bl->flags & P_BIGKEY;
630 break;
631 case P_RINTERNAL:
632 src = GETRINTERNAL(h, nxt);
633 nbytes = NRINTERNAL;
634 isbigkey = 0;
635 break;
636 case P_RLEAF:
637 src = rl = GETRLEAF(h, nxt);
638 nbytes = NRLEAF(rl);
639 isbigkey = 0;
640 break;
641 default:
642 abort();
643 }
644
645 /*
646 * If the key/data pairs are substantial fractions of the max
647 * possible size for the page, it's possible to get situations
648 * where we decide to try and copy too much onto the left page.
649 * Make sure that doesn't happen.
650 */
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651 if ((skip <= off &&
652 used + nbytes + sizeof(indx_t) >= full) || nxt == top - 1) {
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653 --off;
654 break;
655 }
656
657 /* Copy the key/data pair, if not the skipped index. */
658 if (skip != off) {
659 ++nxt;
660
661 l->linp[off] = l->upper -= nbytes;
662 memmove((char *)l + l->upper, src, nbytes);
663 }
664
665 used += nbytes + sizeof(indx_t);
666 if (used >= half) {
667 if (!isbigkey || bigkeycnt == 3)
668 break;
669 else
670 ++bigkeycnt;
671 }
672 }
673
674 /*
675 * Off is the last offset that's valid for the left page.
676 * Nxt is the first offset to be placed on the right page.
677 */
678 l->lower += (off + 1) * sizeof(indx_t);
679
680 /*
681 * If splitting the page that the cursor was on, the cursor has to be
682 * adjusted to point to the same record as before the split. If the
683 * cursor is at or past the skipped slot, the cursor is incremented by
684 * one. If the cursor is on the right page, it is decremented by the
685 * number of records split to the left page.
686 */
687 c = &t->bt_cursor;
688 if (F_ISSET(c, CURS_INIT) && c->pg.pgno == h->pgno) {
689 if (c->pg.index >= skip)
690 ++c->pg.index;
691 if (c->pg.index < nxt) /* Left page. */
692 c->pg.pgno = l->pgno;
693 else { /* Right page. */
694 c->pg.pgno = r->pgno;
695 c->pg.index -= nxt;
696 }
697 }
698
699 /*
700 * If the skipped index was on the left page, just return that page.
701 * Otherwise, adjust the skip index to reflect the new position on
702 * the right page.
703 */
704 if (skip <= off) {
10f84ad9 705 skip = MAX_PAGE_OFFSET;
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706 rval = l;
707 } else {
708 rval = r;
709 *pskip -= nxt;
710 }
711
712 for (off = 0; nxt < top; ++off) {
713 if (skip == nxt) {
714 ++off;
10f84ad9 715 skip = MAX_PAGE_OFFSET;
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716 }
717 switch (h->flags & P_TYPE) {
718 case P_BINTERNAL:
719 src = bi = GETBINTERNAL(h, nxt);
720 nbytes = NBINTERNAL(bi->ksize);
721 break;
722 case P_BLEAF:
723 src = bl = GETBLEAF(h, nxt);
724 nbytes = NBLEAF(bl);
725 break;
726 case P_RINTERNAL:
727 src = GETRINTERNAL(h, nxt);
728 nbytes = NRINTERNAL;
729 break;
730 case P_RLEAF:
731 src = rl = GETRLEAF(h, nxt);
732 nbytes = NRLEAF(rl);
733 break;
734 default:
735 abort();
736 }
737 ++nxt;
738 r->linp[off] = r->upper -= nbytes;
739 memmove((char *)r + r->upper, src, nbytes);
740 }
741 r->lower += off * sizeof(indx_t);
742
743 /* If the key is being appended to the page, adjust the index. */
744 if (skip == top)
745 r->lower += sizeof(indx_t);
746
747 return (rval);
748}
749
750/*
751 * BT_PRESERVE -- Mark a chain of pages as used by an internal node.
752 *
753 * Chains of indirect blocks pointed to by leaf nodes get reclaimed when the
754 * record that references them gets deleted. Chains pointed to by internal
755 * pages never get deleted. This routine marks a chain as pointed to by an
756 * internal page.
757 *
758 * Parameters:
759 * t: tree
760 * pg: page number of first page in the chain.
761 *
762 * Returns:
763 * RET_SUCCESS, RET_ERROR.
764 */
765static int
c9fbf0d3 766bt_preserve(BTREE *t, pgno_t pg)
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767{
768 PAGE *h;
769
770 if ((h = mpool_get(t->bt_mp, pg, 0)) == NULL)
771 return (RET_ERROR);
772 h->flags |= P_PRESERVE;
773 mpool_put(t->bt_mp, h, MPOOL_DIRTY);
774 return (RET_SUCCESS);
775}
776
777/*
778 * REC_TOTAL -- Return the number of recno entries below a page.
779 *
780 * Parameters:
781 * h: page
782 *
783 * Returns:
784 * The number of recno entries below a page.
785 *
786 * XXX
787 * These values could be set by the bt_psplit routine. The problem is that the
788 * entry has to be popped off of the stack etc. or the values have to be passed
789 * all the way back to bt_split/bt_rroot and it's not very clean.
790 */
791static recno_t
c9fbf0d3 792rec_total(PAGE *h)
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793{
794 recno_t recs;
795 indx_t nxt, top;
796
797 for (recs = 0, nxt = 0, top = NEXTINDEX(h); nxt < top; ++nxt)
798 recs += GETRINTERNAL(h, nxt)->nrecs;
799 return (recs);
800}