db/btree/bt_open.c

   1 /*
   2  * Copyright (c) 1999 Apple Computer, Inc. All rights reserved.
   3  *
   4  * @APPLE_LICENSE_HEADER_START@
   5  *
   6  * The contents of this file constitute Original Code as defined in and
   7  * are subject to the Apple Public Source License Version 1.1 (the
   8  * "License").  You may not use this file except in compliance with the
   9  * License.  Please obtain a copy of the License at
  10  * http://www.apple.com/publicsource and read it before using this file.
  11  *
  12  * This Original Code and all software distributed under the License are
  13  * distributed on an "AS IS" basis, WITHOUT WARRANTY OF ANY KIND, EITHER
  14  * EXPRESS OR IMPLIED, AND APPLE HEREBY DISCLAIMS ALL SUCH WARRANTIES,
  15  * INCLUDING WITHOUT LIMITATION, ANY WARRANTIES OF MERCHANTABILITY,
  16  * FITNESS FOR A PARTICULAR PURPOSE OR NON-INFRINGEMENT.  Please see the
  17  * License for the specific language governing rights and limitations
  18  * under the License.
  19  *
  20  * @APPLE_LICENSE_HEADER_END@
  21  */
  22 /*
  23  * Copyright (c) 1990, 1993
  24  *      The Regents of the University of California.  All rights reserved.
  25  *
  26  * This code is derived from software contributed to Berkeley by
  27  * Mike Olson.
  28  *
  29  * Redistribution and use in source and binary forms, with or without
  30  * modification, are permitted provided that the following conditions
  31  * are met:
  32  * 1. Redistributions of source code must retain the above copyright
  33  *    notice, this list of conditions and the following disclaimer.
  34  * 2. Redistributions in binary form must reproduce the above copyright
  35  *    notice, this list of conditions and the following disclaimer in the
  36  *    documentation and/or other materials provided with the distribution.
  37  * 3. All advertising materials mentioning features or use of this software
  38  *    must display the following acknowledgement:
  39  *      This product includes software developed by the University of
  40  *      California, Berkeley and its contributors.
  41  * 4. Neither the name of the University nor the names of its contributors
  42  *    may be used to endorse or promote products derived from this software
  43  *    without specific prior written permission.
  44  *
  45  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
  46  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  47  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
  48  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
  49  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
  50  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
  51  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
  52  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
  53  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
  54  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  55  * SUCH DAMAGE.
  56  */
  57
  58
  59 /*
  60  * Implementation of btree access method for 4.4BSD.
  61  *
  62  * The design here was originally based on that of the btree access method
  63  * used in the Postgres database system at UC Berkeley.  This implementation
  64  * is wholly independent of the Postgres code.
  65  */
  66
  67 #include <sys/param.h>
  68 #include <sys/stat.h>
  69
  70 #include <errno.h>
  71 #include <fcntl.h>
  72 #include <limits.h>
  73 #include <signal.h>
  74 #include <stdio.h>
  75 #include <stdlib.h>
  76 #include <string.h>
  77 #include <unistd.h>
  78
  79 #include <db.h>
  80 #include "btree.h"
  81
  82 static int byteorder __P((void));
  83 static int nroot __P((BTREE *));
  84 static int tmp __P((void));
  85
  86 /*
  87  * __BT_OPEN -- Open a btree.
  88  *
  89  * Creates and fills a DB struct, and calls the routine that actually
  90  * opens the btree.
  91  *
  92  * Parameters:
  93  *      fname:  filename (NULL for in-memory trees)
  94  *      flags:  open flag bits
  95  *      mode:   open permission bits
  96  *      b:      BTREEINFO pointer
  97  *
  98  * Returns:
  99  *      NULL on failure, pointer to DB on success.
 100  *
 101  */
 102 DB *
 103 __bt_open(fname, flags, mode, openinfo, dflags)
 104         const char *fname;
 105         int flags, mode, dflags;
 106         const BTREEINFO *openinfo;
 107 {
 108         struct stat sb;
 109         BTMETA m;
 110         BTREE *t;
 111         BTREEINFO b;
 112         DB *dbp;
 113         pgno_t ncache;
 114         ssize_t nr;
 115         int machine_lorder;
 116
 117         t = NULL;
 118
 119         /*
 120          * Intention is to make sure all of the user's selections are okay
 121          * here and then use them without checking.  Can't be complete, since
 122          * we don't know the right page size, lorder or flags until the backing
 123          * file is opened.  Also, the file's page size can cause the cachesize
 124          * to change.
 125          */
 126         machine_lorder = byteorder();
 127         if (openinfo) {
 128                 b = *openinfo;
 129
 130                 /* Flags: R_DUP. */
 131                 if (b.flags & ~(R_DUP))
 132                         goto einval;
 133
 134                 /*
 135                  * Page size must be indx_t aligned and >= MINPSIZE.  Default
 136                  * page size is set farther on, based on the underlying file
 137                  * transfer size.
 138                  */
 139                 if (b.psize &&
 140                     (b.psize < MINPSIZE || b.psize > MAX_PAGE_OFFSET + 1 ||
 141                     b.psize & sizeof(indx_t) - 1))
 142                         goto einval;
 143
 144                 /* Minimum number of keys per page; absolute minimum is 2. */
 145                 if (b.minkeypage) {
 146                         if (b.minkeypage < 2)
 147                                 goto einval;
 148                 } else
 149                         b.minkeypage = DEFMINKEYPAGE;
 150
 151                 /* If no comparison, use default comparison and prefix. */
 152                 if (b.compare == NULL) {
 153                         b.compare = __bt_defcmp;
 154                         if (b.prefix == NULL)
 155                                 b.prefix = __bt_defpfx;
 156                 }
 157
 158                 if (b.lorder == 0)
 159                         b.lorder = machine_lorder;
 160         } else {
 161                 b.compare = __bt_defcmp;
 162                 b.cachesize = 0;
 163                 b.flags = 0;
 164                 b.lorder = machine_lorder;
 165                 b.minkeypage = DEFMINKEYPAGE;
 166                 b.prefix = __bt_defpfx;
 167                 b.psize = 0;
 168         }
 169
 170         /* Check for the ubiquitous PDP-11. */
 171         if (b.lorder != BIG_ENDIAN && b.lorder != LITTLE_ENDIAN)
 172                 goto einval;
 173
 174         /* Allocate and initialize DB and BTREE structures. */
 175         if ((t = (BTREE *)malloc(sizeof(BTREE))) == NULL)
 176                 goto err;
 177         memset(t, 0, sizeof(BTREE));
 178         t->bt_bcursor.pgno = P_INVALID;
 179         t->bt_fd = -1;                  /* Don't close unopened fd on error. */
 180         t->bt_lorder = b.lorder;
 181         t->bt_order = NOT;
 182         t->bt_cmp = b.compare;
 183         t->bt_pfx = b.prefix;
 184         t->bt_rfd = -1;
 185
 186         if ((t->bt_dbp = dbp = (DB *)malloc(sizeof(DB))) == NULL)
 187                 goto err;
 188         t->bt_flags = 0;
 189         if (t->bt_lorder != machine_lorder)
 190                 SET(t, B_NEEDSWAP);
 191
 192         dbp->type = DB_BTREE;
 193         dbp->internal = t;
 194         dbp->close = __bt_close;
 195         dbp->del = __bt_delete;
 196         dbp->fd = __bt_fd;
 197         dbp->get = __bt_get;
 198         dbp->put = __bt_put;
 199         dbp->seq = __bt_seq;
 200         dbp->sync = __bt_sync;
 201
 202         /*
 203          * If no file name was supplied, this is an in-memory btree and we
 204          * open a backing temporary file.  Otherwise, it's a disk-based tree.
 205          */
 206         if (fname) {
 207                 switch(flags & O_ACCMODE) {
 208                 case O_RDONLY:
 209                         SET(t, B_RDONLY);
 210                         break;
 211                 case O_RDWR:
 212                         break;
 213                 case O_WRONLY:
 214                 default:
 215                         goto einval;
 216                 }
 217
 218                 if ((t->bt_fd = open(fname, flags, mode)) < 0)
 219                         goto err;
 220
 221         } else {
 222                 if ((flags & O_ACCMODE) != O_RDWR)
 223                         goto einval;
 224                 if ((t->bt_fd = tmp()) == -1)
 225                         goto err;
 226                 SET(t, B_INMEM);
 227         }
 228
 229         if (fcntl(t->bt_fd, F_SETFD, 1) == -1)
 230                 goto err;
 231
 232         if (fstat(t->bt_fd, &sb))
 233                 goto err;
 234         if (sb.st_size) {
 235                 nr = read(t->bt_fd, &m, sizeof(BTMETA));
 236                 if (nr < 0)
 237                         goto err;
 238                 if (nr != sizeof(BTMETA))
 239                         goto eftype;
 240
 241                 /*
 242                  * Read in the meta-data.  This can change the notion of what
 243                  * the lorder, page size and flags are, and, when the page size
 244                  * changes, the cachesize value can change too.  If the user
 245                  * specified the wrong byte order for an existing database, we
 246                  * don't bother to return an error, we just clear the NEEDSWAP
 247                  * bit.
 248                  */
 249                 if (m.m_magic == BTREEMAGIC)
 250                         CLR(t, B_NEEDSWAP);
 251                 else {
 252                         SET(t, B_NEEDSWAP);
 253                         M_32_SWAP(m.m_magic);
 254                         M_32_SWAP(m.m_version);
 255                         M_32_SWAP(m.m_psize);
 256                         M_32_SWAP(m.m_free);
 257                         M_32_SWAP(m.m_nrecs);
 258                         M_32_SWAP(m.m_flags);
 259                 }
 260                 if (m.m_magic != BTREEMAGIC || m.m_version != BTREEVERSION)
 261                         goto eftype;
 262                 if (m.m_psize < MINPSIZE || m.m_psize > MAX_PAGE_OFFSET + 1 ||
 263                     m.m_psize & sizeof(indx_t) - 1)
 264                         goto eftype;
 265                 if (m.m_flags & ~SAVEMETA)
 266                         goto eftype;
 267                 b.psize = m.m_psize;
 268                 t->bt_flags |= m.m_flags;
 269                 t->bt_free = m.m_free;
 270                 t->bt_nrecs = m.m_nrecs;
 271         } else {
 272                 /*
 273                  * Set the page size to the best value for I/O to this file.
 274                  * Don't overflow the page offset type.
 275                  */
 276                 if (b.psize == 0) {
 277                         b.psize = sb.st_blksize;
 278                         if (b.psize < MINPSIZE)
 279                                 b.psize = MINPSIZE;
 280                         if (b.psize > MAX_PAGE_OFFSET + 1)
 281                                 b.psize = MAX_PAGE_OFFSET + 1;
 282                 }
 283
 284                 /* Set flag if duplicates permitted. */
 285                 if (!(b.flags & R_DUP))
 286                         SET(t, B_NODUPS);
 287
 288                 t->bt_free = P_INVALID;
 289                 t->bt_nrecs = 0;
 290                 SET(t, B_METADIRTY);
 291         }
 292
 293         t->bt_psize = b.psize;
 294
 295         /* Set the cache size; must be a multiple of the page size. */
 296         if (b.cachesize && b.cachesize & b.psize - 1)
 297                 b.cachesize += (~b.cachesize & b.psize - 1) + 1;
 298         if (b.cachesize < b.psize * MINCACHE)
 299                 b.cachesize = b.psize * MINCACHE;
 300
 301         /* Calculate number of pages to cache. */
 302         ncache = (b.cachesize + t->bt_psize - 1) / t->bt_psize;
 303
 304         /*
 305          * The btree data structure requires that at least two keys can fit on
 306          * a page, but other than that there's no fixed requirement.  The user
 307          * specified a minimum number per page, and we translated that into the
 308          * number of bytes a key/data pair can use before being placed on an
 309          * overflow page.  This calculation includes the page header, the size
 310          * of the index referencing the leaf item and the size of the leaf item
 311          * structure.  Also, don't let the user specify a minkeypage such that
 312          * a key/data pair won't fit even if both key and data are on overflow
 313          * pages.
 314          */
 315         t->bt_ovflsize = (t->bt_psize - BTDATAOFF) / b.minkeypage -
 316             (sizeof(indx_t) + NBLEAFDBT(0, 0));
 317         if (t->bt_ovflsize < NBLEAFDBT(NOVFLSIZE, NOVFLSIZE) + sizeof(indx_t))
 318                 t->bt_ovflsize =
 319                     NBLEAFDBT(NOVFLSIZE, NOVFLSIZE) + sizeof(indx_t);
 320
 321         /* Initialize the buffer pool. */
 322         if ((t->bt_mp =
 323             mpool_open(NULL, t->bt_fd, t->bt_psize, ncache)) == NULL)
 324                 goto err;
 325         if (!ISSET(t, B_INMEM))
 326                 mpool_filter(t->bt_mp, __bt_pgin, __bt_pgout, t);
 327
 328         /* Create a root page if new tree. */
 329         if (nroot(t) == RET_ERROR)
 330                 goto err;
 331
 332         /* Global flags. */
 333         if (dflags & DB_LOCK)
 334                 SET(t, B_DB_LOCK);
 335         if (dflags & DB_SHMEM)
 336                 SET(t, B_DB_SHMEM);
 337         if (dflags & DB_TXN)
 338                 SET(t, B_DB_TXN);
 339
 340         return (dbp);
 341
 342 einval: errno = EINVAL;
 343         goto err;
 344
 345 eftype: errno = EFTYPE;
 346         goto err;
 347
 348 err:    if (t) {
 349                 if (t->bt_dbp)
 350                         free(t->bt_dbp);
 351                 if (t->bt_fd != -1)
 352                         (void)close(t->bt_fd);
 353                 free(t);
 354         }
 355         return (NULL);
 356 }
 357
 358 /*
 359  * NROOT -- Create the root of a new tree.
 360  *
 361  * Parameters:
 362  *      t:      tree
 363  *
 364  * Returns:
 365  *      RET_ERROR, RET_SUCCESS
 366  */
 367 static int
 368 nroot(t)
 369         BTREE *t;
 370 {
 371         PAGE *meta, *root;
 372         pgno_t npg;
 373
 374         if ((meta = mpool_get(t->bt_mp, 0, 0)) != NULL) {
 375                 mpool_put(t->bt_mp, meta, 0);
 376                 return (RET_SUCCESS);
 377         }
 378         if (errno != EINVAL)
 379                 return (RET_ERROR);
 380
 381         if ((meta = mpool_new(t->bt_mp, &npg)) == NULL)
 382                 return (RET_ERROR);
 383
 384         if ((root = mpool_new(t->bt_mp, &npg)) == NULL)
 385                 return (RET_ERROR);
 386
 387         if (npg != P_ROOT)
 388                 return (RET_ERROR);
 389         root->pgno = npg;
 390         root->prevpg = root->nextpg = P_INVALID;
 391         root->lower = BTDATAOFF;
 392         root->upper = t->bt_psize;
 393         root->flags = P_BLEAF;
 394         memset(meta, 0, t->bt_psize);
 395         mpool_put(t->bt_mp, meta, MPOOL_DIRTY);
 396         mpool_put(t->bt_mp, root, MPOOL_DIRTY);
 397         return (RET_SUCCESS);
 398 }
 399
 400 static int
 401 tmp()
 402 {
 403         sigset_t set, oset;
 404         int fd;
 405         char *envtmp;
 406         char path[MAXPATHLEN];
 407
 408         envtmp = getenv("TMPDIR");
 409         (void)snprintf(path,
 410             sizeof(path), "%s/bt.XXXXXX", envtmp ? envtmp : "/tmp");
 411
 412         (void)sigfillset(&set);
 413         (void)sigprocmask(SIG_BLOCK, &set, &oset);
 414         if ((fd = mkstemp(path)) != -1)
 415                 (void)unlink(path);
 416         (void)sigprocmask(SIG_SETMASK, &oset, NULL);
 417         return(fd);
 418 }
 419
 420 static int
 421 byteorder()
 422 {
 423         u_int32_t x;
 424         u_char *p;
 425
 426         x = 0x01020304;
 427         p = (u_char *)&x;
 428         switch (*p) {
 429         case 1:
 430                 return (BIG_ENDIAN);
 431         case 4:
 432                 return (LITTLE_ENDIAN);
 433         default:
 434                 return (0);
 435         }
 436 }
 437
 438 int
 439 __bt_fd(dbp)
 440         const DB *dbp;
 441 {
 442         BTREE *t;
 443
 444         t = dbp->internal;
 445
 446         /* Toss any page pinned across calls. */
 447         if (t->bt_pinned != NULL) {
 448                 mpool_put(t->bt_mp, t->bt_pinned, 0);
 449                 t->bt_pinned = NULL;
 450         }
 451
 452         /* In-memory database can't have a file descriptor. */
 453         if (ISSET(t, B_INMEM)) {
 454                 errno = ENOENT;
 455                 return (-1);
 456         }
 457         return (t->bt_fd);
 458 }