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_page.c 8.7 (Berkeley) 8/16/94"; 35 #endif /* LIBC_SCCS and not lint */ 36 #include <sys/cdefs.h> 37 __FBSDID("$FreeBSD$"); 38 39 /* 40 * PACKAGE: hashing 41 * 42 * DESCRIPTION: 43 * Page manipulation for hashing package. 44 * 45 * ROUTINES: 46 * 47 * External 48 * __get_page 49 * __add_ovflpage 50 * Internal 51 * overflow_page 52 * open_temp 53 */ 54 55 #include "namespace.h" 56 #include <sys/param.h> 57 58 #include <errno.h> 59 #include <fcntl.h> 60 #include <signal.h> 61 #include <stdio.h> 62 #include <stdlib.h> 63 #include <string.h> 64 #include <unistd.h> 65 #ifdef DEBUG 66 #include <assert.h> 67 #endif 68 #include "un-namespace.h" 69 #include "libc_private.h" 70 71 #include <db.h> 72 #include "hash.h" 73 #include "page.h" 74 #include "extern.h" 75 76 static u_int32_t *fetch_bitmap(HTAB *, int); 77 static u_int32_t first_free(u_int32_t); 78 static int open_temp(HTAB *); 79 static u_int16_t overflow_page(HTAB *); 80 static void putpair(char *, const DBT *, const DBT *); 81 static void squeeze_key(u_int16_t *, const DBT *, const DBT *); 82 static int ugly_split(HTAB *, u_int32_t, BUFHEAD *, BUFHEAD *, int, int); 83 84 #define PAGE_INIT(P) { \ 85 ((u_int16_t *)(P))[0] = 0; \ 86 ((u_int16_t *)(P))[1] = hashp->BSIZE - 3 * sizeof(u_int16_t); \ 87 ((u_int16_t *)(P))[2] = hashp->BSIZE; \ 88 } 89 90 /* 91 * This is called AFTER we have verified that there is room on the page for 92 * the pair (PAIRFITS has returned true) so we go right ahead and start moving 93 * stuff on. 94 */ 95 static void 96 putpair(char *p, const DBT *key, const DBT *val) 97 { 98 u_int16_t *bp, n, off; 99 100 bp = (u_int16_t *)p; 101 102 /* Enter the key first. */ 103 n = bp[0]; 104 105 off = OFFSET(bp) - key->size; 106 memmove(p + off, key->data, key->size); 107 bp[++n] = off; 108 109 /* Now the data. */ 110 off -= val->size; 111 memmove(p + off, val->data, val->size); 112 bp[++n] = off; 113 114 /* Adjust page info. */ 115 bp[0] = n; 116 bp[n + 1] = off - ((n + 3) * sizeof(u_int16_t)); 117 bp[n + 2] = off; 118 } 119 120 /* 121 * Returns: 122 * 0 OK 123 * -1 error 124 */ 125 int 126 __delpair(HTAB *hashp, BUFHEAD *bufp, int ndx) 127 { 128 u_int16_t *bp, newoff, pairlen; 129 int n; 130 131 bp = (u_int16_t *)bufp->page; 132 n = bp[0]; 133 134 if (bp[ndx + 1] < REAL_KEY) 135 return (__big_delete(hashp, bufp)); 136 if (ndx != 1) 137 newoff = bp[ndx - 1]; 138 else 139 newoff = hashp->BSIZE; 140 pairlen = newoff - bp[ndx + 1]; 141 142 if (ndx != (n - 1)) { 143 /* Hard Case -- need to shuffle keys */ 144 int i; 145 char *src = bufp->page + (int)OFFSET(bp); 146 char *dst = src + (int)pairlen; 147 memmove(dst, src, bp[ndx + 1] - OFFSET(bp)); 148 149 /* Now adjust the pointers */ 150 for (i = ndx + 2; i <= n; i += 2) { 151 if (bp[i + 1] == OVFLPAGE) { 152 bp[i - 2] = bp[i]; 153 bp[i - 1] = bp[i + 1]; 154 } else { 155 bp[i - 2] = bp[i] + pairlen; 156 bp[i - 1] = bp[i + 1] + pairlen; 157 } 158 } 159 if (ndx == hashp->cndx) { 160 /* 161 * We just removed pair we were "pointing" to. 162 * By moving back the cndx we ensure subsequent 163 * hash_seq() calls won't skip over any entries. 164 */ 165 hashp->cndx -= 2; 166 } 167 } 168 /* Finally adjust the page data */ 169 bp[n] = OFFSET(bp) + pairlen; 170 bp[n - 1] = bp[n + 1] + pairlen + 2 * sizeof(u_int16_t); 171 bp[0] = n - 2; 172 hashp->NKEYS--; 173 174 bufp->flags |= BUF_MOD; 175 return (0); 176 } 177 /* 178 * Returns: 179 * 0 ==> OK 180 * -1 ==> Error 181 */ 182 int 183 __split_page(HTAB *hashp, u_int32_t obucket, u_int32_t nbucket) 184 { 185 BUFHEAD *new_bufp, *old_bufp; 186 u_int16_t *ino; 187 char *np; 188 DBT key, val; 189 int n, ndx, retval; 190 u_int16_t copyto, diff, off, moved; 191 char *op; 192 193 copyto = (u_int16_t)hashp->BSIZE; 194 off = (u_int16_t)hashp->BSIZE; 195 old_bufp = __get_buf(hashp, obucket, NULL, 0); 196 if (old_bufp == NULL) 197 return (-1); 198 new_bufp = __get_buf(hashp, nbucket, NULL, 0); 199 if (new_bufp == NULL) 200 return (-1); 201 202 old_bufp->flags |= (BUF_MOD | BUF_PIN); 203 new_bufp->flags |= (BUF_MOD | BUF_PIN); 204 205 ino = (u_int16_t *)(op = old_bufp->page); 206 np = new_bufp->page; 207 208 moved = 0; 209 210 for (n = 1, ndx = 1; n < ino[0]; n += 2) { 211 if (ino[n + 1] < REAL_KEY) { 212 retval = ugly_split(hashp, obucket, old_bufp, new_bufp, 213 (int)copyto, (int)moved); 214 old_bufp->flags &= ~BUF_PIN; 215 new_bufp->flags &= ~BUF_PIN; 216 return (retval); 217 218 } 219 key.data = (u_char *)op + ino[n]; 220 key.size = off - ino[n]; 221 222 if (__call_hash(hashp, key.data, key.size) == obucket) { 223 /* Don't switch page */ 224 diff = copyto - off; 225 if (diff) { 226 copyto = ino[n + 1] + diff; 227 memmove(op + copyto, op + ino[n + 1], 228 off - ino[n + 1]); 229 ino[ndx] = copyto + ino[n] - ino[n + 1]; 230 ino[ndx + 1] = copyto; 231 } else 232 copyto = ino[n + 1]; 233 ndx += 2; 234 } else { 235 /* Switch page */ 236 val.data = (u_char *)op + ino[n + 1]; 237 val.size = ino[n] - ino[n + 1]; 238 putpair(np, &key, &val); 239 moved += 2; 240 } 241 242 off = ino[n + 1]; 243 } 244 245 /* Now clean up the page */ 246 ino[0] -= moved; 247 FREESPACE(ino) = copyto - sizeof(u_int16_t) * (ino[0] + 3); 248 OFFSET(ino) = copyto; 249 250 #ifdef DEBUG3 251 (void)fprintf(stderr, "split %d/%d\n", 252 ((u_int16_t *)np)[0] / 2, 253 ((u_int16_t *)op)[0] / 2); 254 #endif 255 /* unpin both pages */ 256 old_bufp->flags &= ~BUF_PIN; 257 new_bufp->flags &= ~BUF_PIN; 258 return (0); 259 } 260 261 /* 262 * Called when we encounter an overflow or big key/data page during split 263 * handling. This is special cased since we have to begin checking whether 264 * the key/data pairs fit on their respective pages and because we may need 265 * overflow pages for both the old and new pages. 266 * 267 * The first page might be a page with regular key/data pairs in which case 268 * we have a regular overflow condition and just need to go on to the next 269 * page or it might be a big key/data pair in which case we need to fix the 270 * big key/data pair. 271 * 272 * Returns: 273 * 0 ==> success 274 * -1 ==> failure 275 */ 276 static int 277 ugly_split(HTAB *hashp, 278 u_int32_t obucket, /* Same as __split_page. */ 279 BUFHEAD *old_bufp, 280 BUFHEAD *new_bufp, 281 int copyto, /* First byte on page which contains key/data values. */ 282 int moved) /* Number of pairs moved to new page. */ 283 { 284 BUFHEAD *bufp; /* Buffer header for ino */ 285 u_int16_t *ino; /* Page keys come off of */ 286 u_int16_t *np; /* New page */ 287 u_int16_t *op; /* Page keys go on to if they aren't moving */ 288 289 BUFHEAD *last_bfp; /* Last buf header OVFL needing to be freed */ 290 DBT key, val; 291 SPLIT_RETURN ret; 292 u_int16_t n, off, ov_addr, scopyto; 293 char *cino; /* Character value of ino */ 294 295 bufp = old_bufp; 296 ino = (u_int16_t *)old_bufp->page; 297 np = (u_int16_t *)new_bufp->page; 298 op = (u_int16_t *)old_bufp->page; 299 last_bfp = NULL; 300 scopyto = (u_int16_t)copyto; /* ANSI */ 301 302 n = ino[0] - 1; 303 while (n < ino[0]) { 304 if (ino[2] < REAL_KEY && ino[2] != OVFLPAGE) { 305 if (__big_split(hashp, old_bufp, 306 new_bufp, bufp, bufp->addr, obucket, &ret)) 307 return (-1); 308 old_bufp = ret.oldp; 309 if (!old_bufp) 310 return (-1); 311 op = (u_int16_t *)old_bufp->page; 312 new_bufp = ret.newp; 313 if (!new_bufp) 314 return (-1); 315 np = (u_int16_t *)new_bufp->page; 316 bufp = ret.nextp; 317 if (!bufp) 318 return (0); 319 cino = (char *)bufp->page; 320 ino = (u_int16_t *)cino; 321 last_bfp = ret.nextp; 322 } else if (ino[n + 1] == OVFLPAGE) { 323 ov_addr = ino[n]; 324 /* 325 * Fix up the old page -- the extra 2 are the fields 326 * which contained the overflow information. 327 */ 328 ino[0] -= (moved + 2); 329 FREESPACE(ino) = 330 scopyto - sizeof(u_int16_t) * (ino[0] + 3); 331 OFFSET(ino) = scopyto; 332 333 bufp = __get_buf(hashp, ov_addr, bufp, 0); 334 if (!bufp) 335 return (-1); 336 337 ino = (u_int16_t *)bufp->page; 338 n = 1; 339 scopyto = hashp->BSIZE; 340 moved = 0; 341 342 if (last_bfp) 343 __free_ovflpage(hashp, last_bfp); 344 last_bfp = bufp; 345 } 346 /* Move regular sized pairs of there are any */ 347 off = hashp->BSIZE; 348 for (n = 1; (n < ino[0]) && (ino[n + 1] >= REAL_KEY); n += 2) { 349 cino = (char *)ino; 350 key.data = (u_char *)cino + ino[n]; 351 key.size = off - ino[n]; 352 val.data = (u_char *)cino + ino[n + 1]; 353 val.size = ino[n] - ino[n + 1]; 354 off = ino[n + 1]; 355 356 if (__call_hash(hashp, key.data, key.size) == obucket) { 357 /* Keep on old page */ 358 if (PAIRFITS(op, (&key), (&val))) 359 putpair((char *)op, &key, &val); 360 else { 361 old_bufp = 362 __add_ovflpage(hashp, old_bufp); 363 if (!old_bufp) 364 return (-1); 365 op = (u_int16_t *)old_bufp->page; 366 putpair((char *)op, &key, &val); 367 } 368 old_bufp->flags |= BUF_MOD; 369 } else { 370 /* Move to new page */ 371 if (PAIRFITS(np, (&key), (&val))) 372 putpair((char *)np, &key, &val); 373 else { 374 new_bufp = 375 __add_ovflpage(hashp, new_bufp); 376 if (!new_bufp) 377 return (-1); 378 np = (u_int16_t *)new_bufp->page; 379 putpair((char *)np, &key, &val); 380 } 381 new_bufp->flags |= BUF_MOD; 382 } 383 } 384 } 385 if (last_bfp) 386 __free_ovflpage(hashp, last_bfp); 387 return (0); 388 } 389 390 /* 391 * Add the given pair to the page 392 * 393 * Returns: 394 * 0 ==> OK 395 * 1 ==> failure 396 */ 397 int 398 __addel(HTAB *hashp, BUFHEAD *bufp, const DBT *key, const DBT *val) 399 { 400 u_int16_t *bp, *sop; 401 int do_expand; 402 403 bp = (u_int16_t *)bufp->page; 404 do_expand = 0; 405 while (bp[0] && (bp[2] < REAL_KEY || bp[bp[0]] < REAL_KEY)) 406 /* Exception case */ 407 if (bp[2] == FULL_KEY_DATA && bp[0] == 2) 408 /* This is the last page of a big key/data pair 409 and we need to add another page */ 410 break; 411 else if (bp[2] < REAL_KEY && bp[bp[0]] != OVFLPAGE) { 412 bufp = __get_buf(hashp, bp[bp[0] - 1], bufp, 0); 413 if (!bufp) 414 return (-1); 415 bp = (u_int16_t *)bufp->page; 416 } else if (bp[bp[0]] != OVFLPAGE) { 417 /* Short key/data pairs, no more pages */ 418 break; 419 } else { 420 /* Try to squeeze key on this page */ 421 if (bp[2] >= REAL_KEY && 422 FREESPACE(bp) >= PAIRSIZE(key, val)) { 423 squeeze_key(bp, key, val); 424 goto stats; 425 } else { 426 bufp = __get_buf(hashp, bp[bp[0] - 1], bufp, 0); 427 if (!bufp) 428 return (-1); 429 bp = (u_int16_t *)bufp->page; 430 } 431 } 432 433 if (PAIRFITS(bp, key, val)) 434 putpair(bufp->page, key, val); 435 else { 436 do_expand = 1; 437 bufp = __add_ovflpage(hashp, bufp); 438 if (!bufp) 439 return (-1); 440 sop = (u_int16_t *)bufp->page; 441 442 if (PAIRFITS(sop, key, val)) 443 putpair((char *)sop, key, val); 444 else 445 if (__big_insert(hashp, bufp, key, val)) 446 return (-1); 447 } 448 stats: 449 bufp->flags |= BUF_MOD; 450 /* 451 * If the average number of keys per bucket exceeds the fill factor, 452 * expand the table. 453 */ 454 hashp->NKEYS++; 455 if (do_expand || 456 (hashp->NKEYS / (hashp->MAX_BUCKET + 1) > hashp->FFACTOR)) 457 return (__expand_table(hashp)); 458 return (0); 459 } 460 461 /* 462 * 463 * Returns: 464 * pointer on success 465 * NULL on error 466 */ 467 BUFHEAD * 468 __add_ovflpage(HTAB *hashp, BUFHEAD *bufp) 469 { 470 u_int16_t *sp, ndx, ovfl_num; 471 #ifdef DEBUG1 472 int tmp1, tmp2; 473 #endif 474 sp = (u_int16_t *)bufp->page; 475 476 /* Check if we are dynamically determining the fill factor */ 477 if (hashp->FFACTOR == DEF_FFACTOR) { 478 hashp->FFACTOR = sp[0] >> 1; 479 if (hashp->FFACTOR < MIN_FFACTOR) 480 hashp->FFACTOR = MIN_FFACTOR; 481 } 482 bufp->flags |= BUF_MOD; 483 ovfl_num = overflow_page(hashp); 484 #ifdef DEBUG1 485 tmp1 = bufp->addr; 486 tmp2 = bufp->ovfl ? bufp->ovfl->addr : 0; 487 #endif 488 if (!ovfl_num || !(bufp->ovfl = __get_buf(hashp, ovfl_num, bufp, 1))) 489 return (NULL); 490 bufp->ovfl->flags |= BUF_MOD; 491 #ifdef DEBUG1 492 (void)fprintf(stderr, "ADDOVFLPAGE: %d->ovfl was %d is now %d\n", 493 tmp1, tmp2, bufp->ovfl->addr); 494 #endif 495 ndx = sp[0]; 496 /* 497 * Since a pair is allocated on a page only if there's room to add 498 * an overflow page, we know that the OVFL information will fit on 499 * the page. 500 */ 501 sp[ndx + 4] = OFFSET(sp); 502 sp[ndx + 3] = FREESPACE(sp) - OVFLSIZE; 503 sp[ndx + 1] = ovfl_num; 504 sp[ndx + 2] = OVFLPAGE; 505 sp[0] = ndx + 2; 506 #ifdef HASH_STATISTICS 507 hash_overflows++; 508 #endif 509 return (bufp->ovfl); 510 } 511 512 /* 513 * Returns: 514 * 0 indicates SUCCESS 515 * -1 indicates FAILURE 516 */ 517 int 518 __get_page(HTAB *hashp, char *p, u_int32_t bucket, int is_bucket, int is_disk, 519 int is_bitmap) 520 { 521 int fd, page, size, rsize; 522 u_int16_t *bp; 523 524 fd = hashp->fp; 525 size = hashp->BSIZE; 526 527 if ((fd == -1) || !is_disk) { 528 PAGE_INIT(p); 529 return (0); 530 } 531 if (is_bucket) 532 page = BUCKET_TO_PAGE(bucket); 533 else 534 page = OADDR_TO_PAGE(bucket); 535 if ((rsize = pread(fd, p, size, (off_t)page << hashp->BSHIFT)) == -1) 536 return (-1); 537 bp = (u_int16_t *)p; 538 if (!rsize) 539 bp[0] = 0; /* We hit the EOF, so initialize a new page */ 540 else 541 if (rsize != size) { 542 errno = EFTYPE; 543 return (-1); 544 } 545 if (!is_bitmap && !bp[0]) { 546 PAGE_INIT(p); 547 } else 548 if (hashp->LORDER != BYTE_ORDER) { 549 int i, max; 550 551 if (is_bitmap) { 552 max = hashp->BSIZE >> 2; /* divide by 4 */ 553 for (i = 0; i < max; i++) 554 M_32_SWAP(((int *)p)[i]); 555 } else { 556 M_16_SWAP(bp[0]); 557 max = bp[0] + 2; 558 for (i = 1; i <= max; i++) 559 M_16_SWAP(bp[i]); 560 } 561 } 562 return (0); 563 } 564 565 /* 566 * Write page p to disk 567 * 568 * Returns: 569 * 0 ==> OK 570 * -1 ==>failure 571 */ 572 int 573 __put_page(HTAB *hashp, char *p, u_int32_t bucket, int is_bucket, int is_bitmap) 574 { 575 int fd, page, size, wsize; 576 577 size = hashp->BSIZE; 578 if ((hashp->fp == -1) && open_temp(hashp)) 579 return (-1); 580 fd = hashp->fp; 581 582 if (hashp->LORDER != BYTE_ORDER) { 583 int i, max; 584 585 if (is_bitmap) { 586 max = hashp->BSIZE >> 2; /* divide by 4 */ 587 for (i = 0; i < max; i++) 588 M_32_SWAP(((int *)p)[i]); 589 } else { 590 max = ((u_int16_t *)p)[0] + 2; 591 for (i = 0; i <= max; i++) 592 M_16_SWAP(((u_int16_t *)p)[i]); 593 } 594 } 595 if (is_bucket) 596 page = BUCKET_TO_PAGE(bucket); 597 else 598 page = OADDR_TO_PAGE(bucket); 599 if ((wsize = pwrite(fd, p, size, (off_t)page << hashp->BSHIFT)) == -1) 600 /* Errno is set */ 601 return (-1); 602 if (wsize != size) { 603 errno = EFTYPE; 604 return (-1); 605 } 606 return (0); 607 } 608 609 #define BYTE_MASK ((1 << INT_BYTE_SHIFT) -1) 610 /* 611 * Initialize a new bitmap page. Bitmap pages are left in memory 612 * once they are read in. 613 */ 614 int 615 __ibitmap(HTAB *hashp, int pnum, int nbits, int ndx) 616 { 617 u_int32_t *ip; 618 int clearbytes, clearints; 619 620 if ((ip = (u_int32_t *)malloc(hashp->BSIZE)) == NULL) 621 return (1); 622 hashp->nmaps++; 623 clearints = ((nbits - 1) >> INT_BYTE_SHIFT) + 1; 624 clearbytes = clearints << INT_TO_BYTE; 625 (void)memset((char *)ip, 0, clearbytes); 626 (void)memset(((char *)ip) + clearbytes, 0xFF, 627 hashp->BSIZE - clearbytes); 628 ip[clearints - 1] = ALL_SET << (nbits & BYTE_MASK); 629 SETBIT(ip, 0); 630 hashp->BITMAPS[ndx] = (u_int16_t)pnum; 631 hashp->mapp[ndx] = ip; 632 return (0); 633 } 634 635 static u_int32_t 636 first_free(u_int32_t map) 637 { 638 u_int32_t i, mask; 639 640 mask = 0x1; 641 for (i = 0; i < BITS_PER_MAP; i++) { 642 if (!(mask & map)) 643 return (i); 644 mask = mask << 1; 645 } 646 return (i); 647 } 648 649 static u_int16_t 650 overflow_page(HTAB *hashp) 651 { 652 u_int32_t *freep; 653 int max_free, offset, splitnum; 654 u_int16_t addr; 655 int bit, first_page, free_bit, free_page, i, in_use_bits, j; 656 #ifdef DEBUG2 657 int tmp1, tmp2; 658 #endif 659 splitnum = hashp->OVFL_POINT; 660 max_free = hashp->SPARES[splitnum]; 661 662 free_page = (max_free - 1) >> (hashp->BSHIFT + BYTE_SHIFT); 663 free_bit = (max_free - 1) & ((hashp->BSIZE << BYTE_SHIFT) - 1); 664 665 /* Look through all the free maps to find the first free block */ 666 first_page = hashp->LAST_FREED >>(hashp->BSHIFT + BYTE_SHIFT); 667 for ( i = first_page; i <= free_page; i++ ) { 668 if (!(freep = (u_int32_t *)hashp->mapp[i]) && 669 !(freep = fetch_bitmap(hashp, i))) 670 return (0); 671 if (i == free_page) 672 in_use_bits = free_bit; 673 else 674 in_use_bits = (hashp->BSIZE << BYTE_SHIFT) - 1; 675 676 if (i == first_page) { 677 bit = hashp->LAST_FREED & 678 ((hashp->BSIZE << BYTE_SHIFT) - 1); 679 j = bit / BITS_PER_MAP; 680 bit = bit & ~(BITS_PER_MAP - 1); 681 } else { 682 bit = 0; 683 j = 0; 684 } 685 for (; bit <= in_use_bits; j++, bit += BITS_PER_MAP) 686 if (freep[j] != ALL_SET) 687 goto found; 688 } 689 690 /* No Free Page Found */ 691 hashp->LAST_FREED = hashp->SPARES[splitnum]; 692 hashp->SPARES[splitnum]++; 693 offset = hashp->SPARES[splitnum] - 694 (splitnum ? hashp->SPARES[splitnum - 1] : 0); 695 696 #define OVMSG "HASH: Out of overflow pages. Increase page size\n" 697 if (offset > SPLITMASK) { 698 if (++splitnum >= NCACHED) { 699 (void)_write(STDERR_FILENO, OVMSG, sizeof(OVMSG) - 1); 700 errno = EFBIG; 701 return (0); 702 } 703 hashp->OVFL_POINT = splitnum; 704 hashp->SPARES[splitnum] = hashp->SPARES[splitnum-1]; 705 hashp->SPARES[splitnum-1]--; 706 offset = 1; 707 } 708 709 /* Check if we need to allocate a new bitmap page */ 710 if (free_bit == (hashp->BSIZE << BYTE_SHIFT) - 1) { 711 free_page++; 712 if (free_page >= NCACHED) { 713 (void)_write(STDERR_FILENO, OVMSG, sizeof(OVMSG) - 1); 714 errno = EFBIG; 715 return (0); 716 } 717 /* 718 * This is tricky. The 1 indicates that you want the new page 719 * allocated with 1 clear bit. Actually, you are going to 720 * allocate 2 pages from this map. The first is going to be 721 * the map page, the second is the overflow page we were 722 * looking for. The init_bitmap routine automatically, sets 723 * the first bit of itself to indicate that the bitmap itself 724 * is in use. We would explicitly set the second bit, but 725 * don't have to if we tell init_bitmap not to leave it clear 726 * in the first place. 727 */ 728 if (__ibitmap(hashp, 729 (int)OADDR_OF(splitnum, offset), 1, free_page)) 730 return (0); 731 hashp->SPARES[splitnum]++; 732 #ifdef DEBUG2 733 free_bit = 2; 734 #endif 735 offset++; 736 if (offset > SPLITMASK) { 737 if (++splitnum >= NCACHED) { 738 (void)_write(STDERR_FILENO, OVMSG, 739 sizeof(OVMSG) - 1); 740 errno = EFBIG; 741 return (0); 742 } 743 hashp->OVFL_POINT = splitnum; 744 hashp->SPARES[splitnum] = hashp->SPARES[splitnum-1]; 745 hashp->SPARES[splitnum-1]--; 746 offset = 0; 747 } 748 } else { 749 /* 750 * Free_bit addresses the last used bit. Bump it to address 751 * the first available bit. 752 */ 753 free_bit++; 754 SETBIT(freep, free_bit); 755 } 756 757 /* Calculate address of the new overflow page */ 758 addr = OADDR_OF(splitnum, offset); 759 #ifdef DEBUG2 760 (void)fprintf(stderr, "OVERFLOW_PAGE: ADDR: %d BIT: %d PAGE %d\n", 761 addr, free_bit, free_page); 762 #endif 763 return (addr); 764 765 found: 766 bit = bit + first_free(freep[j]); 767 SETBIT(freep, bit); 768 #ifdef DEBUG2 769 tmp1 = bit; 770 tmp2 = i; 771 #endif 772 /* 773 * Bits are addressed starting with 0, but overflow pages are addressed 774 * beginning at 1. Bit is a bit addressnumber, so we need to increment 775 * it to convert it to a page number. 776 */ 777 bit = 1 + bit + (i * (hashp->BSIZE << BYTE_SHIFT)); 778 if (bit >= hashp->LAST_FREED) 779 hashp->LAST_FREED = bit - 1; 780 781 /* Calculate the split number for this page */ 782 for (i = 0; (i < splitnum) && (bit > hashp->SPARES[i]); i++); 783 offset = (i ? bit - hashp->SPARES[i - 1] : bit); 784 if (offset >= SPLITMASK) { 785 (void)_write(STDERR_FILENO, OVMSG, sizeof(OVMSG) - 1); 786 errno = EFBIG; 787 return (0); /* Out of overflow pages */ 788 } 789 addr = OADDR_OF(i, offset); 790 #ifdef DEBUG2 791 (void)fprintf(stderr, "OVERFLOW_PAGE: ADDR: %d BIT: %d PAGE %d\n", 792 addr, tmp1, tmp2); 793 #endif 794 795 /* Allocate and return the overflow page */ 796 return (addr); 797 } 798 799 /* 800 * Mark this overflow page as free. 801 */ 802 void 803 __free_ovflpage(HTAB *hashp, BUFHEAD *obufp) 804 { 805 u_int16_t addr; 806 u_int32_t *freep; 807 int bit_address, free_page, free_bit; 808 u_int16_t ndx; 809 810 addr = obufp->addr; 811 #ifdef DEBUG1 812 (void)fprintf(stderr, "Freeing %d\n", addr); 813 #endif 814 ndx = (((u_int16_t)addr) >> SPLITSHIFT); 815 bit_address = 816 (ndx ? hashp->SPARES[ndx - 1] : 0) + (addr & SPLITMASK) - 1; 817 if (bit_address < hashp->LAST_FREED) 818 hashp->LAST_FREED = bit_address; 819 free_page = (bit_address >> (hashp->BSHIFT + BYTE_SHIFT)); 820 free_bit = bit_address & ((hashp->BSIZE << BYTE_SHIFT) - 1); 821 822 if (!(freep = hashp->mapp[free_page])) 823 freep = fetch_bitmap(hashp, free_page); 824 #ifdef DEBUG 825 /* 826 * This had better never happen. It means we tried to read a bitmap 827 * that has already had overflow pages allocated off it, and we 828 * failed to read it from the file. 829 */ 830 if (!freep) 831 assert(0); 832 #endif 833 CLRBIT(freep, free_bit); 834 #ifdef DEBUG2 835 (void)fprintf(stderr, "FREE_OVFLPAGE: ADDR: %d BIT: %d PAGE %d\n", 836 obufp->addr, free_bit, free_page); 837 #endif 838 __reclaim_buf(hashp, obufp); 839 } 840 841 /* 842 * Returns: 843 * 0 success 844 * -1 failure 845 */ 846 static int 847 open_temp(HTAB *hashp) 848 { 849 sigset_t set, oset; 850 int len; 851 char *envtmp = NULL; 852 char path[MAXPATHLEN]; 853 854 if (issetugid() == 0) 855 envtmp = getenv("TMPDIR"); 856 len = snprintf(path, 857 sizeof(path), "%s/_hash.XXXXXX", envtmp ? envtmp : "/tmp"); 858 if (len < 0 || len >= (int)sizeof(path)) { 859 errno = ENAMETOOLONG; 860 return (-1); 861 } 862 863 /* Block signals; make sure file goes away at process exit. */ 864 (void)sigfillset(&set); 865 (void)__libc_sigprocmask(SIG_BLOCK, &set, &oset); 866 if ((hashp->fp = mkostemp(path, O_CLOEXEC)) != -1) 867 (void)unlink(path); 868 (void)__libc_sigprocmask(SIG_SETMASK, &oset, (sigset_t *)NULL); 869 return (hashp->fp != -1 ? 0 : -1); 870 } 871 872 /* 873 * We have to know that the key will fit, but the last entry on the page is 874 * an overflow pair, so we need to shift things. 875 */ 876 static void 877 squeeze_key(u_int16_t *sp, const DBT *key, const DBT *val) 878 { 879 char *p; 880 u_int16_t free_space, n, off, pageno; 881 882 p = (char *)sp; 883 n = sp[0]; 884 free_space = FREESPACE(sp); 885 off = OFFSET(sp); 886 887 pageno = sp[n - 1]; 888 off -= key->size; 889 sp[n - 1] = off; 890 memmove(p + off, key->data, key->size); 891 off -= val->size; 892 sp[n] = off; 893 memmove(p + off, val->data, val->size); 894 sp[0] = n + 2; 895 sp[n + 1] = pageno; 896 sp[n + 2] = OVFLPAGE; 897 FREESPACE(sp) = free_space - PAIRSIZE(key, val); 898 OFFSET(sp) = off; 899 } 900 901 static u_int32_t * 902 fetch_bitmap(HTAB *hashp, int ndx) 903 { 904 if (ndx >= hashp->nmaps) 905 return (NULL); 906 if ((hashp->mapp[ndx] = (u_int32_t *)malloc(hashp->BSIZE)) == NULL) 907 return (NULL); 908 if (__get_page(hashp, 909 (char *)hashp->mapp[ndx], hashp->BITMAPS[ndx], 0, 1, 1)) { 910 free(hashp->mapp[ndx]); 911 return (NULL); 912 } 913 return (hashp->mapp[ndx]); 914 } 915 916 #ifdef DEBUG4 917 int 918 print_chain(int addr) 919 { 920 BUFHEAD *bufp; 921 short *bp, oaddr; 922 923 (void)fprintf(stderr, "%d ", addr); 924 bufp = __get_buf(hashp, addr, NULL, 0); 925 bp = (short *)bufp->page; 926 while (bp[0] && ((bp[bp[0]] == OVFLPAGE) || 927 ((bp[0] > 2) && bp[2] < REAL_KEY))) { 928 oaddr = bp[bp[0] - 1]; 929 (void)fprintf(stderr, "%d ", (int)oaddr); 930 bufp = __get_buf(hashp, (int)oaddr, bufp, 0); 931 bp = (short *)bufp->page; 932 } 933 (void)fprintf(stderr, "\n"); 934 } 935 #endif 936