db/hash/FreeBSD/hash_bigkey.c

   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  * Margo Seltzer.
   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.
  16  * 4. Neither the name of the University nor the names of its contributors
  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.
  31  */
  32
  33 #if defined(LIBC_SCCS) && !defined(lint)
  34 static char sccsid[] = "@(#)hash_bigkey.c       8.3 (Berkeley) 5/31/94";
  35 #endif /* LIBC_SCCS and not lint */
  36 #include <sys/cdefs.h>
  37 __FBSDID("$FreeBSD: src/lib/libc/db/hash/hash_bigkey.c,v 1.10 2009/03/28 06:47:05 delphij Exp $");
  38
  39 /*
  40  * PACKAGE: hash
  41  * DESCRIPTION:
  42  *      Big key/data handling for the hashing package.
  43  *
  44  * ROUTINES:
  45  * External
  46  *      __big_keydata
  47  *      __big_split
  48  *      __big_insert
  49  *      __big_return
  50  *      __big_delete
  51  *      __find_last_page
  52  * Internal
  53  *      collect_key
  54  *      collect_data
  55  */
  56
  57 #include <sys/param.h>
  58
  59 #include <errno.h>
  60 #include <stdio.h>
  61 #include <stdlib.h>
  62 #include <string.h>
  63
  64 #ifdef DEBUG
  65 #include <assert.h>
  66 #endif
  67
  68 #include <db.h>
  69 #include "hash.h"
  70 #include "page.h"
  71 #include "hash_extern.h"
  72
  73 static int collect_key(HTAB *, BUFHEAD *, int, DBT *, int);
  74 static int collect_data(HTAB *, BUFHEAD *, int, int);
  75
  76 /*
  77  * Big_insert
  78  *
  79  * You need to do an insert and the key/data pair is too big
  80  *
  81  * Returns:
  82  * 0 ==> OK
  83  *-1 ==> ERROR
  84  */
  85 int
  86 __big_insert(HTAB *hashp, BUFHEAD *bufp, const DBT *key, const DBT *val)
  87 {
  88         u_int16_t *p;
  89         int key_size, n;
  90         unsigned int val_size;
  91         u_int16_t space, move_bytes, off;
  92         char *cp, *key_data, *val_data;
  93
  94         cp = bufp->page;                /* Character pointer of p. */
  95         p = (u_int16_t *)cp;
  96
  97         key_data = (char *)key->data;
  98         key_size = key->size;
  99         val_data = (char *)val->data;
 100         val_size = val->size;
 101
 102         /* First move the Key */
 103         for (space = FREESPACE(p) - BIGOVERHEAD; key_size;
 104             space = FREESPACE(p) - BIGOVERHEAD) {
 105                 move_bytes = MIN(space, key_size);
 106                 off = OFFSET(p) - move_bytes;
 107                 memmove(cp + off, key_data, move_bytes);
 108                 key_size -= move_bytes;
 109                 key_data += move_bytes;
 110                 n = p[0];
 111                 p[++n] = off;
 112                 p[0] = ++n;
 113                 FREESPACE(p) = off - PAGE_META(n);
 114                 OFFSET(p) = off;
 115                 p[n] = PARTIAL_KEY;
 116                 bufp = __add_ovflpage(hashp, bufp);
 117                 if (!bufp)
 118                         return (-1);
 119                 n = p[0];
 120                 if (!key_size) {
 121                         space = FREESPACE(p);
 122                         if (space) {
 123                                 move_bytes = MIN(space, val_size);
 124                                 /*
 125                                  * If the data would fit exactly in the
 126                                  * remaining space, we must overflow it to the
 127                                  * next page; otherwise the invariant that the
 128                                  * data must end on a page with FREESPACE
 129                                  * non-zero would fail.
 130                                  */
 131                                 if (space == val_size && val_size == val->size)
 132                                         goto toolarge;
 133                                 off = OFFSET(p) - move_bytes;
 134                                 memmove(cp + off, val_data, move_bytes);
 135                                 val_data += move_bytes;
 136                                 val_size -= move_bytes;
 137                                 p[n] = off;
 138                                 p[n - 2] = FULL_KEY_DATA;
 139                                 FREESPACE(p) = FREESPACE(p) - move_bytes;
 140                                 OFFSET(p) = off;
 141                         } else {
 142                         toolarge:
 143                                 p[n - 2] = FULL_KEY;
 144                         }
 145                 }
 146                 p = (u_int16_t *)bufp->page;
 147                 cp = bufp->page;
 148                 bufp->flags |= BUF_MOD;
 149         }
 150
 151         /* Now move the data */
 152         for (space = FREESPACE(p) - BIGOVERHEAD; val_size;
 153             space = FREESPACE(p) - BIGOVERHEAD) {
 154                 move_bytes = MIN(space, val_size);
 155                 /*
 156                  * Here's the hack to make sure that if the data ends on the
 157                  * same page as the key ends, FREESPACE is at least one.
 158                  */
 159                 if (space == val_size && val_size == val->size)
 160                         move_bytes--;
 161                 off = OFFSET(p) - move_bytes;
 162                 memmove(cp + off, val_data, move_bytes);
 163                 val_size -= move_bytes;
 164                 val_data += move_bytes;
 165                 n = p[0];
 166                 p[++n] = off;
 167                 p[0] = ++n;
 168                 FREESPACE(p) = off - PAGE_META(n);
 169                 OFFSET(p) = off;
 170                 if (val_size) {
 171                         p[n] = FULL_KEY;
 172                         bufp = __add_ovflpage(hashp, bufp);
 173                         if (!bufp)
 174                                 return (-1);
 175                         cp = bufp->page;
 176                         p = (u_int16_t *)cp;
 177                 } else
 178                         p[n] = FULL_KEY_DATA;
 179                 bufp->flags |= BUF_MOD;
 180         }
 181         return (0);
 182 }
 183
 184 /*
 185  * Called when bufp's page  contains a partial key (index should be 1)
 186  *
 187  * All pages in the big key/data pair except bufp are freed.  We cannot
 188  * free bufp because the page pointing to it is lost and we can't get rid
 189  * of its pointer.
 190  *
 191  * Returns:
 192  * 0 => OK
 193  *-1 => ERROR
 194  */
 195 int
 196 __big_delete(HTAB *hashp, BUFHEAD *bufp)
 197 {
 198         BUFHEAD *last_bfp, *rbufp;
 199         u_int16_t *bp, pageno;
 200         int key_done, n;
 201
 202         rbufp = bufp;
 203         last_bfp = NULL;
 204         bp = (u_int16_t *)bufp->page;
 205         pageno = 0;
 206         key_done = 0;
 207
 208         while (!key_done || (bp[2] != FULL_KEY_DATA)) {
 209                 if (bp[2] == FULL_KEY || bp[2] == FULL_KEY_DATA)
 210                         key_done = 1;
 211
 212                 /*
 213                  * If there is freespace left on a FULL_KEY_DATA page, then
 214                  * the data is short and fits entirely on this page, and this
 215                  * is the last page.
 216                  */
 217                 if (bp[2] == FULL_KEY_DATA && FREESPACE(bp))
 218                         break;
 219                 pageno = bp[bp[0] - 1];
 220                 rbufp->flags |= BUF_MOD;
 221                 rbufp = __get_buf(hashp, pageno, rbufp, 0);
 222                 if (last_bfp)
 223                         __free_ovflpage(hashp, last_bfp);
 224                 last_bfp = rbufp;
 225                 if (!rbufp)
 226                         return (-1);            /* Error. */
 227                 bp = (u_int16_t *)rbufp->page;
 228         }
 229
 230         /*
 231          * If we get here then rbufp points to the last page of the big
 232          * key/data pair.  Bufp points to the first one -- it should now be
 233          * empty pointing to the next page after this pair.  Can't free it
 234          * because we don't have the page pointing to it.
 235          */
 236
 237         /* This is information from the last page of the pair. */
 238         n = bp[0];
 239         pageno = bp[n - 1];
 240
 241         /* Now, bp is the first page of the pair. */
 242         bp = (u_int16_t *)bufp->page;
 243         if (n > 2) {
 244                 /* There is an overflow page. */
 245                 bp[1] = pageno;
 246                 bp[2] = OVFLPAGE;
 247                 bufp->ovfl = rbufp->ovfl;
 248         } else
 249                 /* This is the last page. */
 250                 bufp->ovfl = NULL;
 251         n -= 2;
 252         bp[0] = n;
 253         FREESPACE(bp) = hashp->BSIZE - PAGE_META(n);
 254         OFFSET(bp) = hashp->BSIZE;
 255
 256         bufp->flags |= BUF_MOD;
 257         if (rbufp)
 258                 __free_ovflpage(hashp, rbufp);
 259         if (last_bfp && last_bfp != rbufp)
 260                 __free_ovflpage(hashp, last_bfp);
 261
 262         hashp->NKEYS--;
 263         return (0);
 264 }
 265 /*
 266  * Returns:
 267  *  0 = key not found
 268  * -1 = get next overflow page
 269  * -2 means key not found and this is big key/data
 270  * -3 error
 271  */
 272 int
 273 __find_bigpair(HTAB *hashp, BUFHEAD *bufp, int ndx, char *key, int size)
 274 {
 275         u_int16_t *bp;
 276         char *p;
 277         int ksize;
 278         u_int16_t bytes;
 279         char *kkey;
 280
 281         bp = (u_int16_t *)bufp->page;
 282         p = bufp->page;
 283         ksize = size;
 284         kkey = key;
 285
 286         for (bytes = hashp->BSIZE - bp[ndx];
 287             bytes <= size && bp[ndx + 1] == PARTIAL_KEY;
 288             bytes = hashp->BSIZE - bp[ndx]) {
 289                 if (memcmp(p + bp[ndx], kkey, bytes))
 290                         return (-2);
 291                 kkey += bytes;
 292                 ksize -= bytes;
 293                 bufp = __get_buf(hashp, bp[ndx + 2], bufp, 0);
 294                 if (!bufp)
 295                         return (-3);
 296                 p = bufp->page;
 297                 bp = (u_int16_t *)p;
 298                 ndx = 1;
 299         }
 300
 301         if (bytes != ksize || memcmp(p + bp[ndx], kkey, bytes)) {
 302 #ifdef HASH_STATISTICS
 303                 ++hash_collisions;
 304 #endif
 305                 return (-2);
 306         } else
 307                 return (ndx);
 308 }
 309
 310 /*
 311  * Given the buffer pointer of the first overflow page of a big pair,
 312  * find the end of the big pair
 313  *
 314  * This will set bpp to the buffer header of the last page of the big pair.
 315  * It will return the pageno of the overflow page following the last page
 316  * of the pair; 0 if there isn't any (i.e. big pair is the last key in the
 317  * bucket)
 318  */
 319 u_int16_t
 320 __find_last_page(HTAB *hashp, BUFHEAD **bpp)
 321 {
 322         BUFHEAD *bufp;
 323         u_int16_t *bp, pageno;
 324         int n;
 325
 326         bufp = *bpp;
 327         bp = (u_int16_t *)bufp->page;
 328         for (;;) {
 329                 n = bp[0];
 330
 331                 /*
 332                  * This is the last page if: the tag is FULL_KEY_DATA and
 333                  * either only 2 entries OVFLPAGE marker is explicit there
 334                  * is freespace on the page.
 335                  */
 336                 if (bp[2] == FULL_KEY_DATA &&
 337                     ((n == 2) || (bp[n] == OVFLPAGE) || (FREESPACE(bp))))
 338                         break;
 339
 340                 pageno = bp[n - 1];
 341                 bufp = __get_buf(hashp, pageno, bufp, 0);
 342                 if (!bufp)
 343                         return (0);     /* Need to indicate an error! */
 344                 bp = (u_int16_t *)bufp->page;
 345         }
 346
 347         *bpp = bufp;
 348         if (bp[0] > 2)
 349                 return (bp[3]);
 350         else
 351                 return (0);
 352 }
 353
 354 /*
 355  * Return the data for the key/data pair that begins on this page at this
 356  * index (index should always be 1).
 357  */
 358 int
 359 __big_return(HTAB *hashp, BUFHEAD *bufp, int ndx, DBT *val, int set_current)
 360 {
 361         BUFHEAD *save_p;
 362         u_int16_t *bp, len, off, save_addr;
 363         char *tp;
 364
 365         bp = (u_int16_t *)bufp->page;
 366         while (bp[ndx + 1] == PARTIAL_KEY) {
 367                 bufp = __get_buf(hashp, bp[bp[0] - 1], bufp, 0);
 368                 if (!bufp)
 369                         return (-1);
 370                 bp = (u_int16_t *)bufp->page;
 371                 ndx = 1;
 372         }
 373
 374         if (bp[ndx + 1] == FULL_KEY) {
 375                 bufp = __get_buf(hashp, bp[bp[0] - 1], bufp, 0);
 376                 if (!bufp)
 377                         return (-1);
 378                 bp = (u_int16_t *)bufp->page;
 379                 save_p = bufp;
 380                 save_addr = save_p->addr;
 381                 off = bp[1];
 382                 len = 0;
 383         } else
 384                 if (!FREESPACE(bp)) {
 385                         /*
 386                          * This is a hack.  We can't distinguish between
 387                          * FULL_KEY_DATA that contains complete data or
 388                          * incomplete data, so we require that if the data
 389                          * is complete, there is at least 1 byte of free
 390                          * space left.
 391                          */
 392                         off = bp[bp[0]];
 393                         len = bp[1] - off;
 394                         save_p = bufp;
 395                         save_addr = bufp->addr;
 396                         bufp = __get_buf(hashp, bp[bp[0] - 1], bufp, 0);
 397                         if (!bufp)
 398                                 return (-1);
 399                         bp = (u_int16_t *)bufp->page;
 400                 } else {
 401                         /* The data is all on one page. */
 402                         tp = (char *)bp;
 403                         off = bp[bp[0]];
 404                         val->data = (u_char *)tp + off;
 405                         val->size = bp[1] - off;
 406                         if (set_current) {
 407                                 if (bp[0] == 2) {       /* No more buckets in
 408                                                          * chain */
 409                                         hashp->cpage = NULL;
 410                                         hashp->cbucket++;
 411                                         hashp->cndx = 1;
 412                                 } else {
 413                                         hashp->cpage = __get_buf(hashp,
 414                                             bp[bp[0] - 1], bufp, 0);
 415                                         if (!hashp->cpage)
 416                                                 return (-1);
 417                                         hashp->cndx = 1;
 418                                         if (!((u_int16_t *)
 419                                             hashp->cpage->page)[0]) {
 420                                                 hashp->cbucket++;
 421                                                 hashp->cpage = NULL;
 422                                         }
 423                                 }
 424                         }
 425                         return (0);
 426                 }
 427
 428         val->size = (size_t)collect_data(hashp, bufp, (int)len, set_current);
 429         if (val->size == (size_t)-1)
 430                 return (-1);
 431         if (save_p->addr != save_addr) {
 432                 /* We are pretty short on buffers. */
 433                 errno = EINVAL;                 /* OUT OF BUFFERS */
 434                 return (-1);
 435         }
 436         memmove(hashp->tmp_buf, (save_p->page) + off, len);
 437         val->data = (u_char *)hashp->tmp_buf;
 438         return (0);
 439 }
 440 /*
 441  * Count how big the total datasize is by recursing through the pages.  Then
 442  * allocate a buffer and copy the data as you recurse up.
 443  */
 444 static int
 445 collect_data(HTAB *hashp, BUFHEAD *bufp, int len, int set)
 446 {
 447         u_int16_t *bp;
 448         char *p;
 449         BUFHEAD *xbp;
 450         u_int16_t save_addr;
 451         int mylen, totlen;
 452
 453         p = bufp->page;
 454         bp = (u_int16_t *)p;
 455         mylen = hashp->BSIZE - bp[1];
 456         save_addr = bufp->addr;
 457
 458         if (bp[2] == FULL_KEY_DATA) {           /* End of Data */
 459                 totlen = len + mylen;
 460                 if (hashp->tmp_buf)
 461                         free(hashp->tmp_buf);
 462                 if ((hashp->tmp_buf = (char *)malloc(totlen)) == NULL)
 463                         return (-1);
 464                 if (set) {
 465                         hashp->cndx = 1;
 466                         if (bp[0] == 2) {       /* No more buckets in chain */
 467                                 hashp->cpage = NULL;
 468                                 hashp->cbucket++;
 469                         } else {
 470                                 hashp->cpage =
 471                                     __get_buf(hashp, bp[bp[0] - 1], bufp, 0);
 472                                 if (!hashp->cpage)
 473                                         return (-1);
 474                                 else if (!((u_int16_t *)hashp->cpage->page)[0]) {
 475                                         hashp->cbucket++;
 476                                         hashp->cpage = NULL;
 477                                 }
 478                         }
 479                 }
 480         } else {
 481                 xbp = __get_buf(hashp, bp[bp[0] - 1], bufp, 0);
 482                 if (!xbp || ((totlen =
 483                     collect_data(hashp, xbp, len + mylen, set)) < 1))
 484                         return (-1);
 485         }
 486         if (bufp->addr != save_addr) {
 487                 errno = EINVAL;                 /* Out of buffers. */
 488                 return (-1);
 489         }
 490         memmove(&hashp->tmp_buf[len], (bufp->page) + bp[1], mylen);
 491         return (totlen);
 492 }
 493
 494 /*
 495  * Fill in the key and data for this big pair.
 496  */
 497 int
 498 __big_keydata(HTAB *hashp, BUFHEAD *bufp, DBT *key, DBT *val, int set)
 499 {
 500         key->size = (size_t)collect_key(hashp, bufp, 0, val, set);
 501         if (key->size == (size_t)-1)
 502                 return (-1);
 503         key->data = (u_char *)hashp->tmp_key;
 504         return (0);
 505 }
 506
 507 /*
 508  * Count how big the total key size is by recursing through the pages.  Then
 509  * collect the data, allocate a buffer and copy the key as you recurse up.
 510  */
 511 static int
 512 collect_key(HTAB *hashp, BUFHEAD *bufp, int len, DBT *val, int set)
 513 {
 514         BUFHEAD *xbp;
 515         char *p;
 516         int mylen, totlen;
 517         u_int16_t *bp, save_addr;
 518
 519         p = bufp->page;
 520         bp = (u_int16_t *)p;
 521         mylen = hashp->BSIZE - bp[1];
 522
 523         save_addr = bufp->addr;
 524         totlen = len + mylen;
 525         if (bp[2] == FULL_KEY || bp[2] == FULL_KEY_DATA) {    /* End of Key. */
 526                 if (hashp->tmp_key != NULL)
 527                         free(hashp->tmp_key);
 528                 if ((hashp->tmp_key = (char *)malloc(totlen)) == NULL)
 529                         return (-1);
 530                 if (__big_return(hashp, bufp, 1, val, set))
 531                         return (-1);
 532         } else {
 533                 xbp = __get_buf(hashp, bp[bp[0] - 1], bufp, 0);
 534                 if (!xbp || ((totlen =
 535                     collect_key(hashp, xbp, totlen, val, set)) < 1))
 536                         return (-1);
 537         }
 538         if (bufp->addr != save_addr) {
 539                 errno = EINVAL;         /* MIS -- OUT OF BUFFERS */
 540                 return (-1);
 541         }
 542         memmove(&hashp->tmp_key[len], (bufp->page) + bp[1], mylen);
 543         return (totlen);
 544 }
 545
 546 /*
 547  * Returns:
 548  *  0 => OK
 549  * -1 => error
 550  */
 551 int
 552 __big_split(HTAB *hashp,
 553     BUFHEAD *op,        /* Pointer to where to put keys that go in old bucket */
 554     BUFHEAD *np,        /* Pointer to new bucket page */
 555     BUFHEAD *big_keyp,  /* Pointer to first page containing the big key/data */
 556     int addr,           /* Address of big_keyp */
 557     u_int32_t obucket,  /* Old Bucket */
 558     SPLIT_RETURN *ret)
 559 {
 560         BUFHEAD *bp, *tmpp;
 561         DBT key, val;
 562         u_int32_t change;
 563         u_int16_t free_space, n, off, *tp;
 564
 565         bp = big_keyp;
 566
 567         /* Now figure out where the big key/data goes */
 568         if (__big_keydata(hashp, big_keyp, &key, &val, 0))
 569                 return (-1);
 570         change = (__call_hash(hashp, key.data, key.size) != obucket);
 571
 572         if ( (ret->next_addr = __find_last_page(hashp, &big_keyp)) ) {
 573                 if (!(ret->nextp =
 574                     __get_buf(hashp, ret->next_addr, big_keyp, 0)))
 575                         return (-1);
 576         } else
 577                 ret->nextp = NULL;
 578
 579         /* Now make one of np/op point to the big key/data pair */
 580 #ifdef DEBUG
 581         assert(np->ovfl == NULL);
 582 #endif
 583         if (change)
 584                 tmpp = np;
 585         else
 586                 tmpp = op;
 587
 588         tmpp->flags |= BUF_MOD;
 589 #ifdef DEBUG1
 590         (void)fprintf(stderr,
 591             "BIG_SPLIT: %d->ovfl was %d is now %d\n", tmpp->addr,
 592             (tmpp->ovfl ? tmpp->ovfl->addr : 0), (bp ? bp->addr : 0));
 593 #endif
 594         tmpp->ovfl = bp;        /* one of op/np point to big_keyp */
 595         tp = (u_int16_t *)tmpp->page;
 596 #ifdef DEBUG
 597         assert(FREESPACE(tp) >= OVFLSIZE);
 598 #endif
 599         n = tp[0];
 600         off = OFFSET(tp);
 601         free_space = FREESPACE(tp);
 602         tp[++n] = (u_int16_t)addr;
 603         tp[++n] = OVFLPAGE;
 604         tp[0] = n;
 605         OFFSET(tp) = off;
 606         FREESPACE(tp) = free_space - OVFLSIZE;
 607
 608         /*
 609          * Finally, set the new and old return values. BIG_KEYP contains a
 610          * pointer to the last page of the big key_data pair. Make sure that
 611          * big_keyp has no following page (2 elements) or create an empty
 612          * following page.
 613          */
 614
 615         ret->newp = np;
 616         ret->oldp = op;
 617
 618         tp = (u_int16_t *)big_keyp->page;
 619         big_keyp->flags |= BUF_MOD;
 620         if (tp[0] > 2) {
 621                 /*
 622                  * There may be either one or two offsets on this page.  If
 623                  * there is one, then the overflow page is linked on normally
 624                  * and tp[4] is OVFLPAGE.  If there are two, tp[4] contains
 625                  * the second offset and needs to get stuffed in after the
 626                  * next overflow page is added.
 627                  */
 628                 n = tp[4];
 629                 free_space = FREESPACE(tp);
 630                 off = OFFSET(tp);
 631                 tp[0] -= 2;
 632                 FREESPACE(tp) = free_space + OVFLSIZE;
 633                 OFFSET(tp) = off;
 634                 tmpp = __add_ovflpage(hashp, big_keyp);
 635                 if (!tmpp)
 636                         return (-1);
 637                 tp[4] = n;
 638         } else
 639                 tmpp = big_keyp;
 640
 641         if (change)
 642                 ret->newp = tmpp;
 643         else
 644                 ret->oldp = tmpp;
 645         return (0);
 646 }