1 /*-
2 * See the file LICENSE for redistribution information.
3 *
4 * Copyright (c) 1996, 1997, 1998, 1999, 2000
5 * Sleepycat Software. All rights reserved.
6 */
7 /*
8 * Copyright (c) 1990, 1993, 1994, 1995, 1996
9 * Keith Bostic. All rights reserved.
10 */
11 /*
12 * Copyright (c) 1990, 1993, 1994, 1995
13 * The Regents of the University of California. All rights reserved.
14 *
15 * This code is derived from software contributed to Berkeley by
16 * Mike Olson.
17 *
18 * Redistribution and use in source and binary forms, with or without
19 * modification, are permitted provided that the following conditions
20 * are met:
21 * 1. Redistributions of source code must retain the above copyright
22 * notice, this list of conditions and the following disclaimer.
23 * 2. Redistributions in binary form must reproduce the above copyright
24 * notice, this list of conditions and the following disclaimer in the
25 * documentation and/or other materials provided with the distribution.
26 * 3. Neither the name of the University nor the names of its contributors
27 * may be used to endorse or promote products derived from this software
28 * without specific prior written permission.
29 *
30 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
31 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
32 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
33 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
34 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
35 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
36 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
37 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
38 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
39 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
40 * SUCH DAMAGE.
41 */
42
43 #include "config.h"
44
45 #ifndef lint
46 static const char revid[] = "$Id: db_overflow.c,v 1.5 2000/06/28 16:47:01 loic Exp $";
47 #endif /* not lint */
48
49 #ifndef NO_SYSTEM_INCLUDES
50 #include <sys/types.h>
51
52 #include <errno.h>
53 #include <string.h>
54 #endif
55
56 #include "db_int.h"
57 #include "db_page.h"
58 #include "db_am.h"
59 #include "db_verify.h"
60
61 /*
62 * Big key/data code.
63 *
64 * Big key and data entries are stored on linked lists of pages. The initial
65 * reference is a structure with the total length of the item and the page
66 * number where it begins. Each entry in the linked list contains a pointer
67 * to the next page of data, and so on.
68 */
69
70 /*
71 * CDB___db_goff --
72 * Get an offpage item.
73 *
74 * PUBLIC: int CDB___db_goff __P((DB *, DBT *,
75 * PUBLIC: u_int32_t, db_pgno_t, void **, u_int32_t *));
76 */
77 int
CDB___db_goff(dbp,dbt,tlen,pgno,bpp,bpsz)78 CDB___db_goff(dbp, dbt, tlen, pgno, bpp, bpsz)
79 DB *dbp;
80 DBT *dbt;
81 u_int32_t tlen;
82 db_pgno_t pgno;
83 void **bpp;
84 u_int32_t *bpsz;
85 {
86 DB_ENV *dbenv;
87 PAGE *h;
88 db_indx_t bytes;
89 u_int32_t curoff, needed, start;
90 u_int8_t *p, *src;
91 int ret;
92
93 dbenv = dbp->dbenv;
94
95 /*
96 * Check if the buffer is big enough; if it is not and we are
97 * allowed to malloc space, then we'll malloc it. If we are
98 * not (DB_DBT_USERMEM), then we'll set the dbt and return
99 * appropriately.
100 */
101 if (F_ISSET(dbt, DB_DBT_PARTIAL)) {
102 start = dbt->doff;
103 needed = dbt->dlen;
104 } else {
105 start = 0;
106 needed = tlen;
107 }
108
109 /* Allocate any necessary memory. */
110 if (F_ISSET(dbt, DB_DBT_USERMEM)) {
111 if (needed > dbt->ulen) {
112 dbt->size = needed;
113 return (ENOMEM);
114 }
115 } else if (F_ISSET(dbt, DB_DBT_MALLOC)) {
116 if ((ret = CDB___os_malloc(dbenv,
117 needed, dbp->db_malloc, &dbt->data)) != 0)
118 return (ret);
119 } else if (F_ISSET(dbt, DB_DBT_REALLOC)) {
120 if ((ret = CDB___os_realloc(dbenv,
121 needed, dbp->db_realloc, &dbt->data)) != 0)
122 return (ret);
123 } else if (*bpsz == 0 || *bpsz < needed) {
124 if ((ret = CDB___os_realloc(dbenv, needed, NULL, bpp)) != 0)
125 return (ret);
126 *bpsz = needed;
127 dbt->data = *bpp;
128 } else
129 dbt->data = *bpp;
130
131 /*
132 * Step through the linked list of pages, copying the data on each
133 * one into the buffer. Never copy more than the total data length.
134 */
135 dbt->size = needed;
136 for (curoff = 0, p = dbt->data; pgno != PGNO_INVALID && needed > 0;) {
137 if ((ret = CDB_memp_fget(dbp->mpf, &pgno, 0, &h)) != 0) {
138 (void)CDB___db_pgerr(dbp, pgno);
139 return (ret);
140 }
141 /* Check if we need any bytes from this page. */
142 if (curoff + OV_LEN(h) >= start) {
143 src = (u_int8_t *)h + P_OVERHEAD;
144 bytes = OV_LEN(h);
145 if (start > curoff) {
146 src += start - curoff;
147 bytes -= start - curoff;
148 }
149 if (bytes > needed)
150 bytes = needed;
151 memcpy(p, src, bytes);
152 p += bytes;
153 needed -= bytes;
154 }
155 curoff += OV_LEN(h);
156 pgno = h->next_pgno;
157 CDB_memp_fput(dbp->mpf, h, 0);
158 }
159 return (0);
160 }
161
162 /*
163 * CDB___db_poff --
164 * Put an offpage item.
165 *
166 * PUBLIC: int CDB___db_poff __P((DBC *, const DBT *, db_pgno_t *));
167 */
168 int
CDB___db_poff(dbc,dbt,pgnop)169 CDB___db_poff(dbc, dbt, pgnop)
170 DBC *dbc;
171 const DBT *dbt;
172 db_pgno_t *pgnop;
173 {
174 DB *dbp;
175 PAGE *pagep, *lastp;
176 DB_LSN new_lsn, null_lsn;
177 DBT tmp_dbt;
178 db_indx_t pagespace;
179 u_int32_t sz;
180 u_int8_t *p;
181 int ret;
182
183 /*
184 * Allocate pages and copy the key/data item into them. Calculate the
185 * number of bytes we get for pages we fill completely with a single
186 * item.
187 */
188 dbp = dbc->dbp;
189 pagespace = P_MAXSPACE(dbp->pgsize);
190
191 lastp = NULL;
192 for (p = dbt->data,
193 sz = dbt->size; sz > 0; p += pagespace, sz -= pagespace) {
194 /*
195 * Reduce pagespace so we terminate the loop correctly and
196 * don't copy too much data.
197 */
198 if (sz < pagespace)
199 pagespace = sz;
200
201 /*
202 * Allocate and initialize a new page and copy all or part of
203 * the item onto the page. If sz is less than pagespace, we
204 * have a partial record.
205 */
206 if ((ret = CDB___db_new(dbc, (P_OVERFLOW | dbp->tags), &pagep)) != 0)
207 return (ret);
208 if (DB_LOGGING(dbc)) {
209 tmp_dbt.data = p;
210 tmp_dbt.size = pagespace;
211 ZERO_LSN(null_lsn);
212 if ((ret = CDB___db_big_log(dbp->dbenv, dbc->txn,
213 &new_lsn, 0, DB_ADD_BIG, dbp->log_fileid,
214 PGNO(pagep), lastp ? PGNO(lastp) : PGNO_INVALID,
215 PGNO_INVALID, &tmp_dbt, &LSN(pagep),
216 lastp == NULL ? &null_lsn : &LSN(lastp),
217 &null_lsn)) != 0)
218 return (ret);
219
220 /* Move lsn onto page. */
221 if (lastp)
222 LSN(lastp) = new_lsn;
223 LSN(pagep) = new_lsn;
224 }
225
226 P_INIT(pagep, dbp->pgsize,
227 PGNO(pagep), PGNO_INVALID, PGNO_INVALID, 0, P_OVERFLOW, dbp->tags);
228 OV_LEN(pagep) = pagespace;
229 OV_REF(pagep) = 1;
230 memcpy((u_int8_t *)pagep + P_OVERHEAD, p, pagespace);
231
232 /*
233 * If this is the first entry, update the user's info.
234 * Otherwise, update the entry on the last page filled
235 * in and release that page.
236 */
237 if (lastp == NULL)
238 *pgnop = PGNO(pagep);
239 else {
240 lastp->next_pgno = PGNO(pagep);
241 pagep->prev_pgno = PGNO(lastp);
242 (void)CDB_memp_fput(dbp->mpf, lastp, DB_MPOOL_DIRTY);
243 }
244 lastp = pagep;
245 }
246 (void)CDB_memp_fput(dbp->mpf, lastp, DB_MPOOL_DIRTY);
247 return (0);
248 }
249
250 /*
251 * CDB___db_ovref --
252 * Increment/decrement the reference count on an overflow page.
253 *
254 * PUBLIC: int CDB___db_ovref __P((DBC *, db_pgno_t, int32_t));
255 */
256 int
CDB___db_ovref(dbc,pgno,adjust)257 CDB___db_ovref(dbc, pgno, adjust)
258 DBC *dbc;
259 db_pgno_t pgno;
260 int32_t adjust;
261 {
262 DB *dbp;
263 PAGE *h;
264 int ret;
265
266 dbp = dbc->dbp;
267 if ((ret = CDB_memp_fget(dbp->mpf, &pgno, 0, &h)) != 0) {
268 (void)CDB___db_pgerr(dbp, pgno);
269 return (ret);
270 }
271
272 if (DB_LOGGING(dbc))
273 if ((ret = CDB___db_ovref_log(dbp->dbenv, dbc->txn,
274 &LSN(h), 0, dbp->log_fileid, h->pgno, adjust,
275 &LSN(h))) != 0)
276 return (ret);
277 OV_REF(h) += adjust;
278
279 (void)CDB_memp_fput(dbp->mpf, h, DB_MPOOL_DIRTY);
280 return (0);
281 }
282
283 /*
284 * CDB___db_doff --
285 * Delete an offpage chain of overflow pages.
286 *
287 * PUBLIC: int CDB___db_doff __P((DBC *, db_pgno_t));
288 */
289 int
CDB___db_doff(dbc,pgno)290 CDB___db_doff(dbc, pgno)
291 DBC *dbc;
292 db_pgno_t pgno;
293 {
294 DB *dbp;
295 PAGE *pagep;
296 DB_LSN null_lsn;
297 DBT tmp_dbt;
298 int ret;
299
300 dbp = dbc->dbp;
301 do {
302 if ((ret = CDB_memp_fget(dbp->mpf, &pgno, 0, &pagep)) != 0) {
303 (void)CDB___db_pgerr(dbp, pgno);
304 return (ret);
305 }
306
307 /*
308 * If it's an overflow page and it's referenced by more than
309 * one key/data item, decrement the reference count and return.
310 */
311 if (TYPE(pagep) == P_OVERFLOW && OV_REF(pagep) > 1) {
312 (void)CDB_memp_fput(dbp->mpf, pagep, 0);
313 return (CDB___db_ovref(dbc, pgno, -1));
314 }
315
316 if (DB_LOGGING(dbc)) {
317 tmp_dbt.data = (u_int8_t *)pagep + P_OVERHEAD;
318 tmp_dbt.size = OV_LEN(pagep);
319 ZERO_LSN(null_lsn);
320 if ((ret = CDB___db_big_log(dbp->dbenv, dbc->txn,
321 &LSN(pagep), 0, DB_REM_BIG, dbp->log_fileid,
322 PGNO(pagep), PREV_PGNO(pagep), NEXT_PGNO(pagep),
323 &tmp_dbt, &LSN(pagep), &null_lsn, &null_lsn)) != 0)
324 return (ret);
325 }
326 pgno = pagep->next_pgno;
327 if ((ret = CDB___db_free(dbc, pagep)) != 0)
328 return (ret);
329 } while (pgno != PGNO_INVALID);
330
331 return (0);
332 }
333
334 /*
335 * CDB___db_moff --
336 * Match on overflow pages.
337 *
338 * Given a starting page number and a key, return <0, 0, >0 to indicate if the
339 * key on the page is less than, equal to or greater than the key specified.
340 * We optimize this by doing chunk at a time comparison unless the user has
341 * specified a comparison function. In this case, we need to materialize
342 * the entire object and call their comparison routine.
343 *
344 * PUBLIC: int CDB___db_moff __P((DB *, const DBT *, db_pgno_t, u_int32_t,
345 * PUBLIC: int (*)(const DBT *, const DBT *), int *));
346 */
347 int
CDB___db_moff(dbp,dbt,pgno,tlen,cmpfunc,cmpp)348 CDB___db_moff(dbp, dbt, pgno, tlen, cmpfunc, cmpp)
349 DB *dbp;
350 const DBT *dbt;
351 db_pgno_t pgno;
352 u_int32_t tlen;
353 int (*cmpfunc) __P((const DBT *, const DBT *));
354 int *cmpp;
355 {
356 PAGE *pagep;
357 DBT local_dbt;
358 void *buf;
359 u_int32_t bufsize, cmp_bytes, key_left;
360 u_int8_t *p1, *p2;
361 int ret;
362
363 /*
364 * If there is a user-specified comparison function, build a
365 * contiguous copy of the key, and call it.
366 */
367 if (cmpfunc != NULL) {
368 memset(&local_dbt, 0, sizeof(local_dbt));
369 buf = NULL;
370 bufsize = 0;
371
372 if ((ret = CDB___db_goff(dbp,
373 &local_dbt, tlen, pgno, &buf, &bufsize)) != 0)
374 return (ret);
375 /* Pass the key as the first argument */
376 *cmpp = cmpfunc(dbt, &local_dbt);
377 CDB___os_free(buf, bufsize);
378 return (0);
379 }
380
381 /* While there are both keys to compare. */
382 for (*cmpp = 0, p1 = dbt->data,
383 key_left = dbt->size; key_left > 0 && pgno != PGNO_INVALID;) {
384 if ((ret = CDB_memp_fget(dbp->mpf, &pgno, 0, &pagep)) != 0)
385 return (ret);
386
387 cmp_bytes = OV_LEN(pagep) < key_left ? OV_LEN(pagep) : key_left;
388 tlen -= cmp_bytes;
389 key_left -= cmp_bytes;
390 for (p2 =
391 (u_int8_t *)pagep + P_OVERHEAD; cmp_bytes-- > 0; ++p1, ++p2)
392 if (*p1 != *p2) {
393 *cmpp = (long)*p1 - (long)*p2;
394 break;
395 }
396 pgno = NEXT_PGNO(pagep);
397 if ((ret = CDB_memp_fput(dbp->mpf, pagep, 0)) != 0)
398 return (ret);
399 if (*cmpp != 0)
400 return (0);
401 }
402 if (key_left > 0) /* DBT is longer than the page key. */
403 *cmpp = 1;
404 else if (tlen > 0) /* DBT is shorter than the page key. */
405 *cmpp = -1;
406 else
407 *cmpp = 0;
408
409 return (0);
410 }
411
412 /*
413 * CDB___db_vrfy_overflow --
414 * Verify overflow page.
415 *
416 * PUBLIC: int CDB___db_vrfy_overflow __P((DB *, VRFY_DBINFO *, PAGE *, db_pgno_t,
417 * PUBLIC: u_int32_t));
418 */
419 int
CDB___db_vrfy_overflow(dbp,vdp,h,pgno,flags)420 CDB___db_vrfy_overflow(dbp, vdp, h, pgno, flags)
421 DB *dbp;
422 VRFY_DBINFO *vdp;
423 PAGE *h;
424 db_pgno_t pgno;
425 u_int32_t flags;
426 {
427 VRFY_PAGEINFO *pip;
428 int isbad, ret, t_ret;
429
430 isbad = 0;
431 if ((ret = CDB___db_vrfy_getpageinfo(vdp, pgno, &pip)) != 0)
432 return (ret);
433
434 if ((ret = CDB___db_vrfy_datapage(dbp, vdp, h, pgno, flags)) != 0) {
435 if (ret == DB_VERIFY_BAD)
436 isbad = 1;
437 else
438 goto err;
439 }
440
441 pip->refcount = OV_REF(h);
442 if (pip->refcount < 1) {
443 EPRINT((dbp->dbenv, "Overflow page %lu has zero reference count",
444 pgno));
445 isbad = 1;
446 }
447
448 /* Just store for now. */
449 pip->olen = HOFFSET(h);
450
451 err: if ((t_ret = CDB___db_vrfy_putpageinfo(vdp, pip)) != 0)
452 ret = t_ret;
453 return ((ret == 0 && isbad == 1) ? DB_VERIFY_BAD : ret);
454 }
455
456 /*
457 * CDB___db_vrfy_ovfl_structure --
458 * Walk a list of overflow pages, avoiding cycles and marking
459 * pages seen.
460 *
461 * PUBLIC: int CDB___db_vrfy_ovfl_structure
462 * PUBLIC: __P((DB *, VRFY_DBINFO *, db_pgno_t, u_int32_t, u_int32_t));
463 */
464 int
CDB___db_vrfy_ovfl_structure(dbp,vdp,pgno,tlen,flags)465 CDB___db_vrfy_ovfl_structure(dbp, vdp, pgno, tlen, flags)
466 DB *dbp;
467 VRFY_DBINFO *vdp;
468 db_pgno_t pgno;
469 u_int32_t tlen;
470 u_int32_t flags;
471 {
472 DB *pgset;
473 VRFY_PAGEINFO *pip;
474 db_pgno_t next, prev;
475 int isbad, p, ret, t_ret;
476 u_int32_t refcount;
477
478 pgset = vdp->pgset;
479 DB_ASSERT(pgset != NULL);
480 isbad = 0;
481
482 /* This shouldn't happen, but just to be sure. */
483 if (!IS_VALID_PGNO(pgno))
484 return (DB_VERIFY_BAD);
485
486 /*
487 * Check the first prev_pgno; it ought to be PGNO_INVALID,
488 * since there's no prev page.
489 */
490 if ((ret = CDB___db_vrfy_getpageinfo(vdp, pgno, &pip)) != 0)
491 return (ret);
492
493 /* The refcount is stored on the first overflow page. */
494 refcount = pip->refcount;
495
496 if (pip->type != P_OVERFLOW) {
497 EPRINT((dbp->dbenv,
498 "Overflow page %lu of invalid type", pgno, pip->type));
499 ret = DB_VERIFY_BAD;
500 goto err; /* Unsafe to continue. */
501 }
502
503 prev = pip->prev_pgno;
504 if (prev != PGNO_INVALID) {
505 EPRINT((dbp->dbenv,
506 "First overflow page %lu has a prev_pgno", pgno));
507 isbad = 1;
508 }
509
510 for (;;) {
511 /*
512 * This is slightly gross. Btree leaf pages reference
513 * individual overflow trees multiple times if the overflow page
514 * is the key to a duplicate set. The reference count does not
515 * reflect this multiple referencing. Thus, if this is called
516 * during the structure verification of a btree leaf page, we
517 * check to see whether we've seen it from a leaf page before
518 * and, if we have, adjust our count of how often we've seen it
519 * accordingly.
520 *
521 * (This will screw up if it's actually referenced--and
522 * correctly refcounted--from two different leaf pages, but
523 * that's a very unlikely brokenness that we're not checking for
524 * anyway.)
525 */
526
527 if (LF_ISSET(ST_OVFL_LEAF)) {
528 if (F_ISSET(pip, VRFY_OVFL_LEAFSEEN)) {
529 if ((ret =
530 CDB___db_vrfy_pgset_dec(pgset, pgno)) != 0)
531 goto err;
532 } else
533 F_SET(pip, VRFY_OVFL_LEAFSEEN);
534 }
535
536 if ((ret = CDB___db_vrfy_pgset_get(pgset, pgno, &p)) != 0)
537 goto err;
538
539 /*
540 * We may have seen this elsewhere, if the overflow entry
541 * has been promoted to an internal page.
542 */
543 if ((u_int32_t)p > refcount) {
544 EPRINT((dbp->dbenv,
545 "Page %lu encountered twice in overflow traversal",
546 pgno));
547 ret = DB_VERIFY_BAD;
548 goto err;
549 }
550 if ((ret = CDB___db_vrfy_pgset_inc(pgset, pgno)) != 0)
551 goto err;
552
553 /* Keep a running tab on how much of the item we've seen. */
554 tlen -= pip->olen;
555
556 next = pip->next_pgno;
557
558 /* Are we there yet? */
559 if (next == PGNO_INVALID)
560 break;
561
562 /*
563 * We've already checked this when we saved it, but just
564 * to be sure...
565 */
566 if (!IS_VALID_PGNO(next)) {
567 DB_ASSERT(0);
568 EPRINT((dbp->dbenv,
569 "Overflow page %lu has bad next_pgno",
570 pgno));
571 ret = DB_VERIFY_BAD;
572 goto err;
573 }
574
575 if ((ret = CDB___db_vrfy_putpageinfo(vdp, pip)) != 0 ||
576 (ret = CDB___db_vrfy_getpageinfo(vdp, next, &pip)) != 0)
577 return (ret);
578 if (pip->prev_pgno != pgno) {
579 EPRINT((dbp->dbenv,
580 "Overflow page %lu has bogus prev_pgno value",
581 next));
582 isbad = 1;
583 /*
584 * It's safe to continue because we have separate
585 * cycle detection.
586 */
587 }
588
589 pgno = next;
590 }
591
592 if (tlen > 0) {
593 isbad = 1;
594 EPRINT((dbp->dbenv,
595 "Overflow item incomplete on page %lu", pgno));
596 }
597
598 err: if ((t_ret = CDB___db_vrfy_putpageinfo(vdp, pip)) != 0 && ret == 0)
599 ret = t_ret;
600 return ((ret == 0 && isbad == 1) ? DB_VERIFY_BAD : ret);
601 }
602
603 /*
604 * CDB___db_safe_goff --
605 * Get an overflow item, very carefully, from an untrusted database,
606 * in the context of the salvager.
607 *
608 * PUBLIC: int CDB___db_safe_goff __P((DB *, VRFY_DBINFO *, db_pgno_t,
609 * PUBLIC: DBT *, void **, u_int32_t));
610 */
611 int
CDB___db_safe_goff(dbp,vdp,pgno,dbt,buf,flags)612 CDB___db_safe_goff(dbp, vdp, pgno, dbt, buf, flags)
613 DB *dbp;
614 VRFY_DBINFO *vdp;
615 db_pgno_t pgno;
616 DBT *dbt;
617 void **buf;
618 u_int32_t flags;
619 {
620 PAGE *h;
621 int ret, err_ret;
622 u_int32_t bytesgot, bytes;
623 u_int8_t *src, *dest;
624
625 ret = DB_VERIFY_BAD;
626 err_ret = 0;
627 bytesgot = bytes = 0;
628
629 while ((pgno != PGNO_INVALID) && (IS_VALID_PGNO(pgno))) {
630 /*
631 * Mark that we're looking at this page; if we've seen it
632 * already, quit.
633 */
634 if ((ret = CDB___db_salvage_markdone(vdp, pgno)) != 0)
635 break;
636
637 if ((ret = CDB_memp_fget(dbp->mpf, &pgno, 0, &h)) != 0)
638 break;
639
640 /*
641 * Make sure it's really an overflow page, unless we're
642 * being aggressive, in which case we pretend it is.
643 */
644 if (!LF_ISSET(DB_AGGRESSIVE) && TYPE(h) != P_OVERFLOW) {
645 ret = DB_VERIFY_BAD;
646 break;
647 }
648
649 src = (u_int8_t *)h + P_OVERHEAD;
650 bytes = OV_LEN(h);
651
652 if (bytes + P_OVERHEAD > dbp->pgsize)
653 bytes = dbp->pgsize - P_OVERHEAD;
654
655 if ((ret = CDB___os_realloc(dbp->dbenv,
656 bytesgot + bytes, 0, buf)) != 0)
657 break;
658
659 dest = (u_int8_t *)*buf + bytesgot;
660 bytesgot += bytes;
661
662 memcpy(dest, src, bytes);
663
664 pgno = NEXT_PGNO(h);
665 /* Not much we can do here--we don't want to quit. */
666 if ((ret = CDB_memp_fput(dbp->mpf, h, 0)) != 0)
667 err_ret = ret;
668 }
669
670 if (ret == 0) {
671 dbt->size = bytesgot;
672 dbt->data = *buf;
673 }
674
675 return ((err_ret != 0 && ret == 0) ? err_ret : ret);
676 }
677