lib/libc/db/hash/hash.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  * 3. 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  * $FreeBSD: src/lib/libc/db/hash/hash.c,v 1.8 2000/01/27 23:06:08 jasone Exp $
  33  * $DragonFly: src/lib/libc/db/hash/hash.c,v 1.9 2005/11/12 23:01:55 swildner Exp $
  34  *
  35  * @(#)hash.c   8.9 (Berkeley) 6/16/94
  36  */
  37
  38 #include "namespace.h"
  39 #include <sys/param.h>
  40 #include <sys/stat.h>
  41
  42 #include <errno.h>
  43 #include <fcntl.h>
  44 #include <stdio.h>
  45 #include <stdlib.h>
  46 #include <string.h>
  47 #include <unistd.h>
  48 #ifdef DEBUG
  49 #include <assert.h>
  50 #endif
  51 #include "un-namespace.h"
  52
  53 #include <db.h>
  54 #include "hash.h"
  55 #include "page.h"
  56 #include "extern.h"
  57
  58 static int   alloc_segs(HTAB *, int);
  59 static int   flush_meta(HTAB *);
  60 static int   hash_access(HTAB *, ACTION, const DBT *, DBT *);
  61 static int   hash_close(DB *);
  62 static int   hash_delete(const DB *, const DBT *, u_int32_t);
  63 static int   hash_fd(const DB *);
  64 static int   hash_get(const DB *, const DBT *, DBT *, u_int32_t);
  65 static int   hash_put(const DB *, DBT *, const DBT *, u_int32_t);
  66 static void *hash_realloc(SEGMENT **, int, int);
  67 static int   hash_seq(const DB *, DBT *, DBT *, u_int32_t);
  68 static int   hash_sync(const DB *, u_int32_t);
  69 static int   hdestroy(HTAB *);
  70 static HTAB *init_hash(HTAB *, const char *, const HASHINFO *);
  71 static int   init_htab(HTAB *, int);
  72 #if BYTE_ORDER == LITTLE_ENDIAN
  73 static void  swap_header(HTAB *);
  74 static void  swap_header_copy(HASHHDR *, HASHHDR *);
  75 #endif
  76
  77 /* Fast arithmetic, relying on powers of 2, */
  78 #define MOD(x, y)               ((x) & ((y) - 1))
  79
  80 #define RETURN_ERROR(ERR, LOC)  { save_errno = ERR; goto LOC; }
  81
  82 /* Return values */
  83 #define SUCCESS  (0)
  84 #define ERROR   (-1)
  85 #define ABNORMAL (1)
  86
  87 #ifdef HASH_STATISTICS
  88 int hash_accesses, hash_collisions, hash_expansions, hash_overflows;
  89 #endif
  90
  91 /************************** INTERFACE ROUTINES ***************************/
  92 /* OPEN/CLOSE */
  93
  94 extern DB *
  95 __hash_open(const char *file, int flags, int mode, const HASHINFO * info,
  96             int dflags __unused)
  97 {
  98         HTAB *hashp;
  99         struct stat statbuf;
 100         DB *dbp;
 101         int bpages, hdrsize, new_table, nsegs, save_errno;
 102
 103         if ((flags & O_ACCMODE) == O_WRONLY) {
 104                 errno = EINVAL;
 105                 return (NULL);
 106         }
 107
 108         if (!(hashp = (HTAB *)calloc(1, sizeof(HTAB))))
 109                 return (NULL);
 110         hashp->fp = -1;
 111
 112         /*
 113          * Even if user wants write only, we need to be able to read
 114          * the actual file, so we need to open it read/write. But, the
 115          * field in the hashp structure needs to be accurate so that
 116          * we can check accesses.
 117          */
 118         hashp->flags = flags;
 119
 120         new_table = 0;
 121         if (!file || (flags & O_TRUNC) ||
 122             (stat(file, &statbuf) && (errno == ENOENT))) {
 123                 if (errno == ENOENT)
 124                         errno = 0; /* Just in case someone looks at errno */
 125                 new_table = 1;
 126         }
 127         if (file) {
 128                 if ((hashp->fp = _open(file, flags, mode)) == -1)
 129                         RETURN_ERROR(errno, error0);
 130
 131                 /* if the .db file is empty, and we had permission to create
 132                    a new .db file, then reinitialize the database */
 133                 if ((flags & O_CREAT) &&
 134                      _fstat(hashp->fp, &statbuf) == 0 && statbuf.st_size == 0)
 135                         new_table = 1;
 136
 137                 _fcntl(hashp->fp, F_SETFD, 1);
 138         }
 139         if (new_table) {
 140                 if (!(hashp = init_hash(hashp, file, info)))
 141                         RETURN_ERROR(errno, error1);
 142         } else {
 143                 /* Table already exists */
 144                 if (info && info->hash)
 145                         hashp->hash = info->hash;
 146                 else
 147                         hashp->hash = __default_hash;
 148
 149                 hdrsize = _read(hashp->fp, &hashp->hdr, sizeof(HASHHDR));
 150 #if BYTE_ORDER == LITTLE_ENDIAN
 151                 swap_header(hashp);
 152 #endif
 153                 if (hdrsize == -1)
 154                         RETURN_ERROR(errno, error1);
 155                 if (hdrsize != sizeof(HASHHDR))
 156                         RETURN_ERROR(EFTYPE, error1);
 157                 /* Verify file type, versions and hash function */
 158                 if (hashp->MAGIC != HASHMAGIC)
 159                         RETURN_ERROR(EFTYPE, error1);
 160 #define OLDHASHVERSION  1
 161                 if (hashp->VERSION != HASHVERSION &&
 162                     hashp->VERSION != OLDHASHVERSION)
 163                         RETURN_ERROR(EFTYPE, error1);
 164                 if (hashp->hash(CHARKEY, sizeof(CHARKEY)) != hashp->H_CHARKEY)
 165                         RETURN_ERROR(EFTYPE, error1);
 166                 /*
 167                  * Figure out how many segments we need.  Max_Bucket is the
 168                  * maximum bucket number, so the number of buckets is
 169                  * max_bucket + 1.
 170                  */
 171                 nsegs = (hashp->MAX_BUCKET + 1 + hashp->SGSIZE - 1) /
 172                          hashp->SGSIZE;
 173                 hashp->nsegs = 0;
 174                 if (alloc_segs(hashp, nsegs))
 175                         /*
 176                          * If alloc_segs fails, table will have been destroyed
 177                          * and errno will have been set.
 178                          */
 179                         return (NULL);
 180                 /* Read in bitmaps */
 181                 bpages = (hashp->SPARES[hashp->OVFL_POINT] +
 182                     (hashp->BSIZE << BYTE_SHIFT) - 1) >>
 183                     (hashp->BSHIFT + BYTE_SHIFT);
 184
 185                 hashp->nmaps = bpages;
 186                 memset(&hashp->mapp[0], 0, bpages * sizeof(u_int32_t *));
 187         }
 188
 189         /* Initialize Buffer Manager */
 190         if (info && info->cachesize)
 191                 __buf_init(hashp, info->cachesize);
 192         else
 193                 __buf_init(hashp, DEF_BUFSIZE);
 194
 195         hashp->new_file = new_table;
 196         hashp->save_file = file && (hashp->flags & O_RDWR);
 197         hashp->cbucket = -1;
 198         if (!(dbp = (DB *)malloc(sizeof(DB)))) {
 199                 save_errno = errno;
 200                 hdestroy(hashp);
 201                 errno = save_errno;
 202                 return (NULL);
 203         }
 204         dbp->internal = hashp;
 205         dbp->close = hash_close;
 206         dbp->del = hash_delete;
 207         dbp->fd = hash_fd;
 208         dbp->get = hash_get;
 209         dbp->put = hash_put;
 210         dbp->seq = hash_seq;
 211         dbp->sync = hash_sync;
 212         dbp->type = DB_HASH;
 213
 214 #ifdef DEBUG
 215         fprintf(stderr,
 216 "%s\n%s%p\n%s%d\n%s%d\n%s%d\n%s%d\n%s%d\n%s%d\n%s%d\n%s%d\n%s%d\n%s%x\n%s%x\n%s%d\n%s%d\n",
 217             "init_htab:",
 218             "TABLE POINTER   ", hashp,
 219             "BUCKET SIZE     ", hashp->BSIZE,
 220             "BUCKET SHIFT    ", hashp->BSHIFT,
 221             "DIRECTORY SIZE  ", hashp->DSIZE,
 222             "SEGMENT SIZE    ", hashp->SGSIZE,
 223             "SEGMENT SHIFT   ", hashp->SSHIFT,
 224             "FILL FACTOR     ", hashp->FFACTOR,
 225             "MAX BUCKET      ", hashp->MAX_BUCKET,
 226             "OVFL POINT      ", hashp->OVFL_POINT,
 227             "LAST FREED      ", hashp->LAST_FREED,
 228             "HIGH MASK       ", hashp->HIGH_MASK,
 229             "LOW  MASK       ", hashp->LOW_MASK,
 230             "NSEGS           ", hashp->nsegs,
 231             "NKEYS           ", hashp->NKEYS);
 232 #endif
 233 #ifdef HASH_STATISTICS
 234         hash_overflows = hash_accesses = hash_collisions = hash_expansions = 0;
 235 #endif
 236         return (dbp);
 237
 238 error1:
 239         if (hashp != NULL)
 240                 _close(hashp->fp);
 241
 242 error0:
 243         free(hashp);
 244         errno = save_errno;
 245         return (NULL);
 246 }
 247
 248 static int
 249 hash_close(DB *dbp)
 250 {
 251         HTAB *hashp;
 252         int retval;
 253
 254         if (!dbp)
 255                 return (ERROR);
 256
 257         hashp = (HTAB *)dbp->internal;
 258         retval = hdestroy(hashp);
 259         free(dbp);
 260         return (retval);
 261 }
 262
 263 static int
 264 hash_fd(const DB *dbp)
 265 {
 266         HTAB *hashp;
 267
 268         if (!dbp)
 269                 return (ERROR);
 270
 271         hashp = (HTAB *)dbp->internal;
 272         if (hashp->fp == -1) {
 273                 errno = ENOENT;
 274                 return (-1);
 275         }
 276         return (hashp->fp);
 277 }
 278
 279 /************************** LOCAL CREATION ROUTINES **********************/
 280 static HTAB *
 281 init_hash(HTAB *hashp, const char *file, const HASHINFO *info)
 282 {
 283         struct stat statbuf;
 284         int nelem;
 285
 286         nelem = 1;
 287         hashp->NKEYS = 0;
 288         hashp->LORDER = BYTE_ORDER;
 289         hashp->BSIZE = DEF_BUCKET_SIZE;
 290         hashp->BSHIFT = DEF_BUCKET_SHIFT;
 291         hashp->SGSIZE = DEF_SEGSIZE;
 292         hashp->SSHIFT = DEF_SEGSIZE_SHIFT;
 293         hashp->DSIZE = DEF_DIRSIZE;
 294         hashp->FFACTOR = DEF_FFACTOR;
 295         hashp->hash = __default_hash;
 296         memset(hashp->SPARES, 0, sizeof(hashp->SPARES));
 297         memset(hashp->BITMAPS, 0, sizeof (hashp->BITMAPS));
 298
 299         /* Fix bucket size to be optimal for file system */
 300         if (file != NULL) {
 301                 if (stat(file, &statbuf))
 302                         return (NULL);
 303                 hashp->BSIZE = statbuf.st_blksize;
 304                 hashp->BSHIFT = __log2(hashp->BSIZE);
 305         }
 306
 307         if (info) {
 308                 if (info->bsize) {
 309                         /* Round pagesize up to power of 2 */
 310                         hashp->BSHIFT = __log2(info->bsize);
 311                         hashp->BSIZE = 1 << hashp->BSHIFT;
 312                         if (hashp->BSIZE > MAX_BSIZE) {
 313                                 errno = EINVAL;
 314                                 return (NULL);
 315                         }
 316                 }
 317                 if (info->ffactor)
 318                         hashp->FFACTOR = info->ffactor;
 319                 if (info->hash)
 320                         hashp->hash = info->hash;
 321                 if (info->nelem)
 322                         nelem = info->nelem;
 323                 if (info->lorder) {
 324                         if (info->lorder != BIG_ENDIAN &&
 325                             info->lorder != LITTLE_ENDIAN) {
 326                                 errno = EINVAL;
 327                                 return (NULL);
 328                         }
 329                         hashp->LORDER = info->lorder;
 330                 }
 331         }
 332         /* init_htab should destroy the table and set errno if it fails */
 333         if (init_htab(hashp, nelem))
 334                 return (NULL);
 335         else
 336                 return (hashp);
 337 }
 338 /*
 339  * This calls alloc_segs which may run out of memory.  Alloc_segs will destroy
 340  * the table and set errno, so we just pass the error information along.
 341  *
 342  * Returns 0 on No Error
 343  */
 344 static int
 345 init_htab(HTAB *hashp, int nelem)
 346 {
 347         int nbuckets, nsegs;
 348         int l2;
 349
 350         /*
 351          * Divide number of elements by the fill factor and determine a
 352          * desired number of buckets.  Allocate space for the next greater
 353          * power of two number of buckets.
 354          */
 355         nelem = (nelem - 1) / hashp->FFACTOR + 1;
 356
 357         l2 = __log2(MAX(nelem, 2));
 358         nbuckets = 1 << l2;
 359
 360         hashp->SPARES[l2] = l2 + 1;
 361         hashp->SPARES[l2 + 1] = l2 + 1;
 362         hashp->OVFL_POINT = l2;
 363         hashp->LAST_FREED = 2;
 364
 365         /* First bitmap page is at: splitpoint l2 page offset 1 */
 366         if (__ibitmap(hashp, OADDR_OF(l2, 1), l2 + 1, 0))
 367                 return (-1);
 368
 369         hashp->MAX_BUCKET = hashp->LOW_MASK = nbuckets - 1;
 370         hashp->HIGH_MASK = (nbuckets << 1) - 1;
 371         hashp->HDRPAGES = ((MAX(sizeof(HASHHDR), MINHDRSIZE) - 1) >>
 372             hashp->BSHIFT) + 1;
 373
 374         nsegs = (nbuckets - 1) / hashp->SGSIZE + 1;
 375         nsegs = 1 << __log2(nsegs);
 376
 377         if (nsegs > hashp->DSIZE)
 378                 hashp->DSIZE = nsegs;
 379         return (alloc_segs(hashp, nsegs));
 380 }
 381
 382 /********************** DESTROY/CLOSE ROUTINES ************************/
 383
 384 /*
 385  * Flushes any changes to the file if necessary and destroys the hashp
 386  * structure, freeing all allocated space.
 387  */
 388 static int
 389 hdestroy(HTAB *hashp)
 390 {
 391         int i, save_errno;
 392
 393         save_errno = 0;
 394
 395 #ifdef HASH_STATISTICS
 396         fprintf(stderr, "hdestroy: accesses %ld collisions %ld\n",
 397             hash_accesses, hash_collisions);
 398         fprintf(stderr, "hdestroy: expansions %ld\n",
 399             hash_expansions);
 400         fprintf(stderr, "hdestroy: overflows %ld\n",
 401             hash_overflows);
 402         fprintf(stderr, "keys %ld maxp %d segmentcount %d\n",
 403             hashp->NKEYS, hashp->MAX_BUCKET, hashp->nsegs);
 404
 405         for (i = 0; i < NCACHED; i++)
 406                 fprintf(stderr,
 407                     "spares[%d] = %d\n", i, hashp->SPARES[i]);
 408 #endif
 409         /*
 410          * Call on buffer manager to free buffers, and if required,
 411          * write them to disk.
 412          */
 413         if (__buf_free(hashp, 1, hashp->save_file))
 414                 save_errno = errno;
 415         if (hashp->dir) {
 416                 free(*hashp->dir);      /* Free initial segments */
 417                 /* Free extra segments */
 418                 while (hashp->exsegs--)
 419                         free(hashp->dir[--hashp->nsegs]);
 420                 free(hashp->dir);
 421         }
 422         if (flush_meta(hashp) && !save_errno)
 423                 save_errno = errno;
 424         /* Free Bigmaps */
 425         for (i = 0; i < hashp->nmaps; i++)
 426                 if (hashp->mapp[i])
 427                         free(hashp->mapp[i]);
 428
 429         if (hashp->fp != -1)
 430                 _close(hashp->fp);
 431
 432         free(hashp);
 433
 434         if (save_errno) {
 435                 errno = save_errno;
 436                 return (ERROR);
 437         }
 438         return (SUCCESS);
 439 }
 440 /*
 441  * Write modified pages to disk
 442  *
 443  * Returns:
 444  *       0 == OK
 445  *      -1 ERROR
 446  */
 447 static int
 448 hash_sync(const DB *dbp, u_int32_t flags)
 449 {
 450         HTAB *hashp;
 451
 452         if (flags != 0) {
 453                 errno = EINVAL;
 454                 return (ERROR);
 455         }
 456
 457         if (!dbp)
 458                 return (ERROR);
 459
 460         hashp = (HTAB *)dbp->internal;
 461         if (!hashp->save_file)
 462                 return (0);
 463         if (__buf_free(hashp, 0, 1) || flush_meta(hashp))
 464                 return (ERROR);
 465         hashp->new_file = 0;
 466         return (0);
 467 }
 468
 469 /*
 470  * Returns:
 471  *       0 == OK
 472  *      -1 indicates that errno should be set
 473  */
 474 static int
 475 flush_meta(HTAB *hashp)
 476 {
 477         HASHHDR *whdrp;
 478 #if BYTE_ORDER == LITTLE_ENDIAN
 479         HASHHDR whdr;
 480 #endif
 481         int fp, i, wsize;
 482
 483         if (!hashp->save_file)
 484                 return (0);
 485         hashp->MAGIC = HASHMAGIC;
 486         hashp->VERSION = HASHVERSION;
 487         hashp->H_CHARKEY = hashp->hash(CHARKEY, sizeof(CHARKEY));
 488
 489         fp = hashp->fp;
 490         whdrp = &hashp->hdr;
 491 #if BYTE_ORDER == LITTLE_ENDIAN
 492         whdrp = &whdr;
 493         swap_header_copy(&hashp->hdr, whdrp);
 494 #endif
 495         if ((lseek(fp, (off_t)0, SEEK_SET) == -1) ||
 496             ((wsize = _write(fp, whdrp, sizeof(HASHHDR))) == -1))
 497                 return (-1);
 498         else
 499                 if (wsize != sizeof(HASHHDR)) {
 500                         errno = EFTYPE;
 501                         hashp->error = errno;
 502                         return (-1);
 503                 }
 504         for (i = 0; i < NCACHED; i++)
 505                 if (hashp->mapp[i])
 506                         if (__put_page(hashp, (char *)hashp->mapp[i],
 507                                 hashp->BITMAPS[i], 0, 1))
 508                                 return (-1);
 509         return (0);
 510 }
 511
 512 /*******************************SEARCH ROUTINES *****************************/
 513 /*
 514  * All the access routines return
 515  *
 516  * Returns:
 517  *       0 on SUCCESS
 518  *       1 to indicate an external ERROR (i.e. key not found, etc)
 519  *      -1 to indicate an internal ERROR (i.e. out of memory, etc)
 520  */
 521 static int
 522 hash_get(const DB *dbp, const DBT *key, DBT *data, u_int32_t flag)
 523 {
 524         HTAB *hashp;
 525
 526         hashp = (HTAB *)dbp->internal;
 527         if (flag) {
 528                 hashp->error = EINVAL;
 529                 errno = EINVAL;
 530                 return (ERROR);
 531         }
 532         return (hash_access(hashp, HASH_GET, key, data));
 533 }
 534
 535 static int
 536 hash_put(const DB *dbp, DBT *key, const DBT *data, u_int32_t flag)
 537 {
 538         HTAB *hashp;
 539
 540         hashp = (HTAB *)dbp->internal;
 541         if (flag && flag != R_NOOVERWRITE) {
 542                 hashp->error = errno = EINVAL;
 543                 return (ERROR);
 544         }
 545         if ((hashp->flags & O_ACCMODE) == O_RDONLY) {
 546                 hashp->error = errno = EPERM;
 547                 return (ERROR);
 548         }
 549         return (hash_access(hashp, flag == R_NOOVERWRITE ?
 550             HASH_PUTNEW : HASH_PUT, key, __DECONST(DBT *, data)));
 551 }
 552
 553 static int
 554 hash_delete(const DB *dbp, const DBT *key, u_int32_t flag)
 555 {
 556         HTAB *hashp;
 557
 558         hashp = (HTAB *)dbp->internal;
 559         if (flag && flag != R_CURSOR) {
 560                 hashp->error = errno = EINVAL;
 561                 return (ERROR);
 562         }
 563         if ((hashp->flags & O_ACCMODE) == O_RDONLY) {
 564                 hashp->error = errno = EPERM;
 565                 return (ERROR);
 566         }
 567         return (hash_access(hashp, HASH_DELETE, key, NULL));
 568 }
 569
 570 /*
 571  * Assume that hashp has been set in wrapper routine.
 572  */
 573 static int
 574 hash_access(HTAB *hashp, ACTION action, const DBT *key, DBT *val)
 575 {
 576         BUFHEAD *rbufp;
 577         BUFHEAD *bufp, *save_bufp;
 578         u_int16_t *bp;
 579         int n, ndx, off, size;
 580         const char *kp;
 581         u_int16_t pageno;
 582
 583 #ifdef HASH_STATISTICS
 584         hash_accesses++;
 585 #endif
 586
 587         off = hashp->BSIZE;
 588         size = key->size;
 589         kp = (char *)key->data;
 590         rbufp = __get_buf(hashp, __call_hash(hashp, kp, size), NULL, 0);
 591         if (!rbufp)
 592                 return (ERROR);
 593         save_bufp = rbufp;
 594
 595         /* Pin the bucket chain */
 596         rbufp->flags |= BUF_PIN;
 597         for (bp = (u_int16_t *)rbufp->page, n = *bp++, ndx = 1; ndx < n;)
 598                 if (bp[1] >= REAL_KEY) {
 599                         /* Real key/data pair */
 600                         if (size == off - *bp &&
 601                             memcmp(kp, rbufp->page + *bp, size) == 0)
 602                                 goto found;
 603                         off = bp[1];
 604 #ifdef HASH_STATISTICS
 605                         hash_collisions++;
 606 #endif
 607                         bp += 2;
 608                         ndx += 2;
 609                 } else if (bp[1] == OVFLPAGE) {
 610                         rbufp = __get_buf(hashp, *bp, rbufp, 0);
 611                         if (!rbufp) {
 612                                 save_bufp->flags &= ~BUF_PIN;
 613                                 return (ERROR);
 614                         }
 615                         /* FOR LOOP INIT */
 616                         bp = (u_int16_t *)rbufp->page;
 617                         n = *bp++;
 618                         ndx = 1;
 619                         off = hashp->BSIZE;
 620                 } else if (bp[1] < REAL_KEY) {
 621                         if ((ndx =
 622                             __find_bigpair(hashp, rbufp, ndx, kp, size)) > 0)
 623                                 goto found;
 624                         if (ndx == -2) {
 625                                 bufp = rbufp;
 626                                 if (!(pageno =
 627                                     __find_last_page(hashp, &bufp))) {
 628                                         ndx = 0;
 629                                         rbufp = bufp;
 630                                         break;  /* FOR */
 631                                 }
 632                                 rbufp = __get_buf(hashp, pageno, bufp, 0);
 633                                 if (!rbufp) {
 634                                         save_bufp->flags &= ~BUF_PIN;
 635                                         return (ERROR);
 636                                 }
 637                                 /* FOR LOOP INIT */
 638                                 bp = (u_int16_t *)rbufp->page;
 639                                 n = *bp++;
 640                                 ndx = 1;
 641                                 off = hashp->BSIZE;
 642                         } else {
 643                                 save_bufp->flags &= ~BUF_PIN;
 644                                 return (ERROR);
 645                         }
 646                 }
 647
 648         /* Not found */
 649         switch (action) {
 650         case HASH_PUT:
 651         case HASH_PUTNEW:
 652                 if (__addel(hashp, rbufp, key, val)) {
 653                         save_bufp->flags &= ~BUF_PIN;
 654                         return (ERROR);
 655                 } else {
 656                         save_bufp->flags &= ~BUF_PIN;
 657                         return (SUCCESS);
 658                 }
 659         case HASH_GET:
 660         case HASH_DELETE:
 661         default:
 662                 save_bufp->flags &= ~BUF_PIN;
 663                 return (ABNORMAL);
 664         }
 665
 666 found:
 667         switch (action) {
 668         case HASH_PUTNEW:
 669                 save_bufp->flags &= ~BUF_PIN;
 670                 return (ABNORMAL);
 671         case HASH_GET:
 672                 bp = (u_int16_t *)rbufp->page;
 673                 if (bp[ndx + 1] < REAL_KEY) {
 674                         if (__big_return(hashp, rbufp, ndx, val, 0))
 675                                 return (ERROR);
 676                 } else {
 677                         val->data = (u_char *)rbufp->page + (int)bp[ndx + 1];
 678                         val->size = bp[ndx] - bp[ndx + 1];
 679                 }
 680                 break;
 681         case HASH_PUT:
 682                 if ((__delpair(hashp, rbufp, ndx)) ||
 683                     (__addel(hashp, rbufp, key, val))) {
 684                         save_bufp->flags &= ~BUF_PIN;
 685                         return (ERROR);
 686                 }
 687                 break;
 688         case HASH_DELETE:
 689                 if (__delpair(hashp, rbufp, ndx))
 690                         return (ERROR);
 691                 break;
 692         default:
 693                 abort();
 694         }
 695         save_bufp->flags &= ~BUF_PIN;
 696         return (SUCCESS);
 697 }
 698
 699 static int
 700 hash_seq(const DB *dbp, DBT *key, DBT *data, u_int32_t flag)
 701 {
 702         u_int32_t bucket;
 703         BUFHEAD *bufp;
 704         HTAB *hashp;
 705         u_int16_t *bp, ndx;
 706
 707         hashp = (HTAB *)dbp->internal;
 708         if (flag && flag != R_FIRST && flag != R_NEXT) {
 709                 hashp->error = errno = EINVAL;
 710                 return (ERROR);
 711         }
 712 #ifdef HASH_STATISTICS
 713         hash_accesses++;
 714 #endif
 715         if ((hashp->cbucket < 0) || (flag == R_FIRST)) {
 716                 hashp->cbucket = 0;
 717                 hashp->cndx = 1;
 718                 hashp->cpage = NULL;
 719         }
 720
 721         for (bp = NULL; !bp || !bp[0]; ) {
 722                 if (!(bufp = hashp->cpage)) {
 723                         for (bucket = hashp->cbucket;
 724                             bucket <= hashp->MAX_BUCKET;
 725                             bucket++, hashp->cndx = 1) {
 726                                 bufp = __get_buf(hashp, bucket, NULL, 0);
 727                                 if (!bufp)
 728                                         return (ERROR);
 729                                 hashp->cpage = bufp;
 730                                 bp = (u_int16_t *)bufp->page;
 731                                 if (bp[0])
 732                                         break;
 733                         }
 734                         hashp->cbucket = bucket;
 735                         if (hashp->cbucket > hashp->MAX_BUCKET) {
 736                                 hashp->cbucket = -1;
 737                                 return (ABNORMAL);
 738                         }
 739                 } else
 740                         bp = (u_int16_t *)hashp->cpage->page;
 741
 742 #ifdef DEBUG
 743                 assert(bp);
 744                 assert(bufp);
 745 #endif
 746                 while (bp[hashp->cndx + 1] == OVFLPAGE) {
 747                         bufp = hashp->cpage =
 748                             __get_buf(hashp, bp[hashp->cndx], bufp, 0);
 749                         if (!bufp)
 750                                 return (ERROR);
 751                         bp = (u_int16_t *)(bufp->page);
 752                         hashp->cndx = 1;
 753                 }
 754                 if (!bp[0]) {
 755                         hashp->cpage = NULL;
 756                         ++hashp->cbucket;
 757                 }
 758         }
 759         ndx = hashp->cndx;
 760         if (bp[ndx + 1] < REAL_KEY) {
 761                 if (__big_keydata(hashp, bufp, key, data, 1))
 762                         return (ERROR);
 763         } else {
 764                 key->data = (u_char *)hashp->cpage->page + bp[ndx];
 765                 key->size = (ndx > 1 ? bp[ndx - 1] : hashp->BSIZE) - bp[ndx];
 766                 data->data = (u_char *)hashp->cpage->page + bp[ndx + 1];
 767                 data->size = bp[ndx] - bp[ndx + 1];
 768                 ndx += 2;
 769                 if (ndx > bp[0]) {
 770                         hashp->cpage = NULL;
 771                         hashp->cbucket++;
 772                         hashp->cndx = 1;
 773                 } else
 774                         hashp->cndx = ndx;
 775         }
 776         return (SUCCESS);
 777 }
 778
 779 /********************************* UTILITIES ************************/
 780
 781 /*
 782  * Returns:
 783  *       0 ==> OK
 784  *      -1 ==> Error
 785  */
 786 extern int
 787 __expand_table(HTAB *hashp)
 788 {
 789         u_int32_t old_bucket, new_bucket;
 790         int dirsize, new_segnum, spare_ndx;
 791
 792 #ifdef HASH_STATISTICS
 793         hash_expansions++;
 794 #endif
 795         new_bucket = ++hashp->MAX_BUCKET;
 796         old_bucket = (hashp->MAX_BUCKET & hashp->LOW_MASK);
 797
 798         new_segnum = new_bucket >> hashp->SSHIFT;
 799
 800         /* Check if we need a new segment */
 801         if (new_segnum >= hashp->nsegs) {
 802                 /* Check if we need to expand directory */
 803                 if (new_segnum >= hashp->DSIZE) {
 804                         /* Reallocate directory */
 805                         dirsize = hashp->DSIZE * sizeof(SEGMENT *);
 806                         if (!hash_realloc(&hashp->dir, dirsize, dirsize << 1))
 807                                 return (-1);
 808                         hashp->DSIZE = dirsize << 1;
 809                 }
 810                 if ((hashp->dir[new_segnum] =
 811                     (SEGMENT)calloc(hashp->SGSIZE, sizeof(SEGMENT))) == NULL)
 812                         return (-1);
 813                 hashp->exsegs++;
 814                 hashp->nsegs++;
 815         }
 816         /*
 817          * If the split point is increasing (MAX_BUCKET's log base 2
 818          * * increases), we need to copy the current contents of the spare
 819          * split bucket to the next bucket.
 820          */
 821         spare_ndx = __log2(hashp->MAX_BUCKET + 1);
 822         if (spare_ndx > hashp->OVFL_POINT) {
 823                 hashp->SPARES[spare_ndx] = hashp->SPARES[hashp->OVFL_POINT];
 824                 hashp->OVFL_POINT = spare_ndx;
 825         }
 826
 827         if (new_bucket > hashp->HIGH_MASK) {
 828                 /* Starting a new doubling */
 829                 hashp->LOW_MASK = hashp->HIGH_MASK;
 830                 hashp->HIGH_MASK = new_bucket | hashp->LOW_MASK;
 831         }
 832         /* Relocate records to the new bucket */
 833         return (__split_page(hashp, old_bucket, new_bucket));
 834 }
 835
 836 /*
 837  * If realloc guarantees that the pointer is not destroyed if the realloc
 838  * fails, then this routine can go away.
 839  */
 840 static void *
 841 hash_realloc(SEGMENT **p_ptr, int oldsize, int newsize)
 842 {
 843         void *p;
 844
 845         if ( (p = malloc(newsize)) ) {
 846                 memmove(p, *p_ptr, oldsize);
 847                 memset((char *)p + oldsize, 0, newsize - oldsize);
 848                 free(*p_ptr);
 849                 *p_ptr = p;
 850         }
 851         return (p);
 852 }
 853
 854 extern u_int32_t
 855 __call_hash(HTAB *hashp, const char *k, int len)
 856 {
 857         int n, bucket;
 858
 859         n = hashp->hash(k, len);
 860         bucket = n & hashp->HIGH_MASK;
 861         if (bucket > hashp->MAX_BUCKET)
 862                 bucket = bucket & hashp->LOW_MASK;
 863         return (bucket);
 864 }
 865
 866 /*
 867  * Allocate segment table.  On error, destroy the table and set errno.
 868  *
 869  * Returns 0 on success
 870  */
 871 static int
 872 alloc_segs(HTAB *hashp, int nsegs)
 873 {
 874         int i;
 875         SEGMENT store;
 876
 877         int save_errno;
 878
 879         if ((hashp->dir =
 880             (SEGMENT *)calloc(hashp->DSIZE, sizeof(SEGMENT *))) == NULL) {
 881                 save_errno = errno;
 882                 hdestroy(hashp);
 883                 errno = save_errno;
 884                 return (-1);
 885         }
 886         /* Allocate segments */
 887         if ((store =
 888             (SEGMENT)calloc(nsegs << hashp->SSHIFT, sizeof(SEGMENT))) == NULL) {
 889                 save_errno = errno;
 890                 hdestroy(hashp);
 891                 errno = save_errno;
 892                 return (-1);
 893         }
 894         for (i = 0; i < nsegs; i++, hashp->nsegs++)
 895                 hashp->dir[i] = &store[i << hashp->SSHIFT];
 896         return (0);
 897 }
 898
 899 #if BYTE_ORDER == LITTLE_ENDIAN
 900 /*
 901  * Hashp->hdr needs to be byteswapped.
 902  */
 903 static void
 904 swap_header_copy(HASHHDR *srcp, HASHHDR *destp)
 905 {
 906         int i;
 907
 908         P_32_COPY(srcp->magic, destp->magic);
 909         P_32_COPY(srcp->version, destp->version);
 910         P_32_COPY(srcp->lorder, destp->lorder);
 911         P_32_COPY(srcp->bsize, destp->bsize);
 912         P_32_COPY(srcp->bshift, destp->bshift);
 913         P_32_COPY(srcp->dsize, destp->dsize);
 914         P_32_COPY(srcp->ssize, destp->ssize);
 915         P_32_COPY(srcp->sshift, destp->sshift);
 916         P_32_COPY(srcp->ovfl_point, destp->ovfl_point);
 917         P_32_COPY(srcp->last_freed, destp->last_freed);
 918         P_32_COPY(srcp->max_bucket, destp->max_bucket);
 919         P_32_COPY(srcp->high_mask, destp->high_mask);
 920         P_32_COPY(srcp->low_mask, destp->low_mask);
 921         P_32_COPY(srcp->ffactor, destp->ffactor);
 922         P_32_COPY(srcp->nkeys, destp->nkeys);
 923         P_32_COPY(srcp->hdrpages, destp->hdrpages);
 924         P_32_COPY(srcp->h_charkey, destp->h_charkey);
 925         for (i = 0; i < NCACHED; i++) {
 926                 P_32_COPY(srcp->spares[i], destp->spares[i]);
 927                 P_16_COPY(srcp->bitmaps[i], destp->bitmaps[i]);
 928         }
 929 }
 930
 931 static void
 932 swap_header(HTAB *hashp)
 933 {
 934         HASHHDR *hdrp;
 935         int i;
 936
 937         hdrp = &hashp->hdr;
 938
 939         M_32_SWAP(hdrp->magic);
 940         M_32_SWAP(hdrp->version);
 941         M_32_SWAP(hdrp->lorder);
 942         M_32_SWAP(hdrp->bsize);
 943         M_32_SWAP(hdrp->bshift);
 944         M_32_SWAP(hdrp->dsize);
 945         M_32_SWAP(hdrp->ssize);
 946         M_32_SWAP(hdrp->sshift);
 947         M_32_SWAP(hdrp->ovfl_point);
 948         M_32_SWAP(hdrp->last_freed);
 949         M_32_SWAP(hdrp->max_bucket);
 950         M_32_SWAP(hdrp->high_mask);
 951         M_32_SWAP(hdrp->low_mask);
 952         M_32_SWAP(hdrp->ffactor);
 953         M_32_SWAP(hdrp->nkeys);
 954         M_32_SWAP(hdrp->hdrpages);
 955         M_32_SWAP(hdrp->h_charkey);
 956         for (i = 0; i < NCACHED; i++) {
 957                 M_32_SWAP(hdrp->spares[i]);
 958                 M_16_SWAP(hdrp->bitmaps[i]);
 959         }
 960 }
 961 #endif