db/btree/bt_open.c

   1 /*
   2  * Copyright (c) 2003 Apple Computer, Inc. All rights reserved.
   3  *
   4  * @APPLE_LICENSE_HEADER_START@
   5  *
   6  * This file contains Original Code and/or Modifications of Original Code
   7  * as defined in and that are subject to the Apple Public Source License
   8  * Version 2.0 (the 'License'). You may not use this file except in
   9  * compliance with the License. Please obtain a copy of the License at
  10  * http://www.opensource.apple.com/apsl/ and read it before using this
  11  * file.
  12  *
  13  * The Original Code and all software distributed under the License are
  14  * distributed on an 'AS IS' basis, WITHOUT WARRANTY OF ANY KIND, EITHER
  15  * EXPRESS OR IMPLIED, AND APPLE HEREBY DISCLAIMS ALL SUCH WARRANTIES,
  16  * INCLUDING WITHOUT LIMITATION, ANY WARRANTIES OF MERCHANTABILITY,
  17  * FITNESS FOR A PARTICULAR PURPOSE, QUIET ENJOYMENT OR NON-INFRINGEMENT.
  18  * Please see the License for the specific language governing rights and
  19  * limitations under the License.
  20  *
  21  * @APPLE_LICENSE_HEADER_END@
  22  */
  23 /*-
  24  * Copyright (c) 1990, 1993, 1994
  25  *      The Regents of the University of California.  All rights reserved.
  26  *
  27  * This code is derived from software contributed to Berkeley by
  28  * Mike Olson.
  29  *
  30  * Redistribution and use in source and binary forms, with or without
  31  * modification, are permitted provided that the following conditions
  32  * are met:
  33  * 1. Redistributions of source code must retain the above copyright
  34  *    notice, this list of conditions and the following disclaimer.
  35  * 2. Redistributions in binary form must reproduce the above copyright
  36  *    notice, this list of conditions and the following disclaimer in the
  37  *    documentation and/or other materials provided with the distribution.
  38  * 3. All advertising materials mentioning features or use of this software
  39  *    must display the following acknowledgement:
  40  *      This product includes software developed by the University of
  41  *      California, Berkeley and its contributors.
  42  * 4. Neither the name of the University nor the names of its contributors
  43  *    may be used to endorse or promote products derived from this software
  44  *    without specific prior written permission.
  45  *
  46  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
  47  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  48  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
  49  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
  50  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
  51  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
  52  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
  53  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
  54  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
  55  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  56  * SUCH DAMAGE.
  57  */
  58
  59 #if defined(LIBC_SCCS) && !defined(lint)
  60 static char sccsid[] = "@(#)bt_open.c   8.10 (Berkeley) 8/17/94";
  61 #endif /* LIBC_SCCS and not lint */
  62 #include <sys/cdefs.h>
  63
  64 /*
  65  * Implementation of btree access method for 4.4BSD.
  66  *
  67  * The design here was originally based on that of the btree access method
  68  * used in the Postgres database system at UC Berkeley.  This implementation
  69  * is wholly independent of the Postgres code.
  70  */
  71
  72 #include <sys/param.h>
  73 #include <sys/stat.h>
  74
  75 #include <errno.h>
  76 #include <fcntl.h>
  77 #include <limits.h>
  78 #include <signal.h>
  79 #include <stdio.h>
  80 #include <stdlib.h>
  81 #include <string.h>
  82 #include <unistd.h>
  83
  84 #include <db.h>
  85 #include "btree.h"
  86
  87 #ifdef DEBUG
  88 #undef  MINPSIZE
  89 #define MINPSIZE        128
  90 #endif
  91
  92 static int byteorder(void);
  93 static int nroot(BTREE *);
  94 static int tmp(void);
  95
  96 /*
  97  * __BT_OPEN -- Open a btree.
  98  *
  99  * Creates and fills a DB struct, and calls the routine that actually
 100  * opens the btree.
 101  *
 102  * Parameters:
 103  *      fname:  filename (NULL for in-memory trees)
 104  *      flags:  open flag bits
 105  *      mode:   open permission bits
 106  *      b:      BTREEINFO pointer
 107  *
 108  * Returns:
 109  *      NULL on failure, pointer to DB on success.
 110  *
 111  */
 112 DB *
 113 __bt_open(fname, flags, mode, openinfo, dflags)
 114         const char *fname;
 115         int flags, mode, dflags;
 116         const BTREEINFO *openinfo;
 117 {
 118         struct stat sb;
 119         BTMETA m;
 120         BTREE *t;
 121         BTREEINFO b;
 122         DB *dbp;
 123         pgno_t ncache;
 124         ssize_t nr;
 125         int machine_lorder;
 126
 127         t = NULL;
 128
 129         /*
 130          * Intention is to make sure all of the user's selections are okay
 131          * here and then use them without checking.  Can't be complete, since
 132          * we don't know the right page size, lorder or flags until the backing
 133          * file is opened.  Also, the file's page size can cause the cachesize
 134          * to change.
 135          */
 136         machine_lorder = byteorder();
 137         if (openinfo) {
 138                 b = *openinfo;
 139
 140                 /* Flags: R_DUP. */
 141                 if (b.flags & ~(R_DUP))
 142                         goto einval;
 143
 144                 /*
 145                  * Page size must be indx_t aligned and >= MINPSIZE.  Default
 146                  * page size is set farther on, based on the underlying file
 147                  * transfer size.
 148                  */
 149                 if (b.psize &&
 150                     (b.psize < MINPSIZE || b.psize > MAX_PAGE_OFFSET + 1 ||
 151                     b.psize & (sizeof(indx_t) - 1) ))
 152                         goto einval;
 153
 154                 /* Minimum number of keys per page; absolute minimum is 2. */
 155                 if (b.minkeypage) {
 156                         if (b.minkeypage < 2)
 157                                 goto einval;
 158                 } else
 159                         b.minkeypage = DEFMINKEYPAGE;
 160
 161                 /* If no comparison, use default comparison and prefix. */
 162                 if (b.compare == NULL) {
 163                         b.compare = __bt_defcmp;
 164                         if (b.prefix == NULL)
 165                                 b.prefix = __bt_defpfx;
 166                 }
 167
 168                 if (b.lorder == 0)
 169                         b.lorder = machine_lorder;
 170         } else {
 171                 b.compare = __bt_defcmp;
 172                 b.cachesize = 0;
 173                 b.flags = 0;
 174                 b.lorder = machine_lorder;
 175                 b.minkeypage = DEFMINKEYPAGE;
 176                 b.prefix = __bt_defpfx;
 177                 b.psize = 0;
 178         }
 179
 180         /* Check for the ubiquitous PDP-11. */
 181         if (b.lorder != BIG_ENDIAN && b.lorder != LITTLE_ENDIAN)
 182                 goto einval;
 183
 184         /* Allocate and initialize DB and BTREE structures. */
 185         if ((t = (BTREE *)malloc(sizeof(BTREE))) == NULL)
 186                 goto err;
 187         memset(t, 0, sizeof(BTREE));
 188         t->bt_fd = -1;                  /* Don't close unopened fd on error. */
 189         t->bt_lorder = b.lorder;
 190         t->bt_order = NOT;
 191         t->bt_cmp = b.compare;
 192         t->bt_pfx = b.prefix;
 193         t->bt_rfd = -1;
 194
 195         if ((t->bt_dbp = dbp = (DB *)malloc(sizeof(DB))) == NULL)
 196                 goto err;
 197         memset(t->bt_dbp, 0, sizeof(DB));
 198         if (t->bt_lorder != machine_lorder)
 199                 F_SET(t, B_NEEDSWAP);
 200
 201         dbp->type = DB_BTREE;
 202         dbp->internal = t;
 203         dbp->close = __bt_close;
 204         dbp->del = __bt_delete;
 205         dbp->fd = __bt_fd;
 206         dbp->get = __bt_get;
 207         dbp->put = __bt_put;
 208         dbp->seq = __bt_seq;
 209         dbp->sync = __bt_sync;
 210
 211         /*
 212          * If no file name was supplied, this is an in-memory btree and we
 213          * open a backing temporary file.  Otherwise, it's a disk-based tree.
 214          */
 215         if (fname) {
 216                 switch (flags & O_ACCMODE) {
 217                 case O_RDONLY:
 218                         F_SET(t, B_RDONLY);
 219                         break;
 220                 case O_RDWR:
 221                         break;
 222                 case O_WRONLY:
 223                 default:
 224                         goto einval;
 225                 }
 226
 227                 if ((t->bt_fd = open(fname, flags, mode)) < 0)
 228                         goto err;
 229
 230         } else {
 231                 if ((flags & O_ACCMODE) != O_RDWR)
 232                         goto einval;
 233                 if ((t->bt_fd = tmp()) == -1)
 234                         goto err;
 235                 F_SET(t, B_INMEM);
 236         }
 237
 238         if (fcntl(t->bt_fd, F_SETFD, 1) == -1)
 239                 goto err;
 240
 241         if (fstat(t->bt_fd, &sb))
 242                 goto err;
 243         if (sb.st_size) {
 244                 if ((nr = read(t->bt_fd, &m, sizeof(BTMETA))) < 0)
 245                         goto err;
 246                 if (nr != sizeof(BTMETA))
 247                         goto eftype;
 248
 249                 /*
 250                  * Read in the meta-data.  This can change the notion of what
 251                  * the lorder, page size and flags are, and, when the page size
 252                  * changes, the cachesize value can change too.  If the user
 253                  * specified the wrong byte order for an existing database, we
 254                  * don't bother to return an error, we just clear the NEEDSWAP
 255                  * bit.
 256                  */
 257                 if (m.magic == BTREEMAGIC)
 258                         F_CLR(t, B_NEEDSWAP);
 259                 else {
 260                         F_SET(t, B_NEEDSWAP);
 261                         M_32_SWAP(m.magic);
 262                         M_32_SWAP(m.version);
 263                         M_32_SWAP(m.psize);
 264                         M_32_SWAP(m.free);
 265                         M_32_SWAP(m.nrecs);
 266                         M_32_SWAP(m.flags);
 267                 }
 268                 if (m.magic != BTREEMAGIC || m.version != BTREEVERSION)
 269                         goto eftype;
 270                 if (m.psize < MINPSIZE || m.psize > MAX_PAGE_OFFSET + 1 ||
 271                     m.psize & (sizeof(indx_t) - 1) )
 272                         goto eftype;
 273                 if (m.flags & ~SAVEMETA)
 274                         goto eftype;
 275                 b.psize = m.psize;
 276                 F_SET(t, m.flags);
 277                 t->bt_free = m.free;
 278                 t->bt_nrecs = m.nrecs;
 279         } else {
 280                 /*
 281                  * Set the page size to the best value for I/O to this file.
 282                  * Don't overflow the page offset type.
 283                  */
 284                 if (b.psize == 0) {
 285                         b.psize = sb.st_blksize;
 286                         if (b.psize < MINPSIZE)
 287                                 b.psize = MINPSIZE;
 288                         if (b.psize > MAX_PAGE_OFFSET + 1)
 289                                 b.psize = MAX_PAGE_OFFSET + 1;
 290                 }
 291
 292                 /* Set flag if duplicates permitted. */
 293                 if (!(b.flags & R_DUP))
 294                         F_SET(t, B_NODUPS);
 295
 296                 t->bt_free = P_INVALID;
 297                 t->bt_nrecs = 0;
 298                 F_SET(t, B_METADIRTY);
 299         }
 300
 301         t->bt_psize = b.psize;
 302
 303         /* Set the cache size; must be a multiple of the page size. */
 304         if (b.cachesize && b.cachesize & (b.psize - 1) )
 305                 b.cachesize += (~b.cachesize & (b.psize - 1) ) + 1;
 306         if (b.cachesize < b.psize * MINCACHE)
 307                 b.cachesize = b.psize * MINCACHE;
 308
 309         /* Calculate number of pages to cache. */
 310         ncache = (b.cachesize + t->bt_psize - 1) / t->bt_psize;
 311
 312         /*
 313          * The btree data structure requires that at least two keys can fit on
 314          * a page, but other than that there's no fixed requirement.  The user
 315          * specified a minimum number per page, and we translated that into the
 316          * number of bytes a key/data pair can use before being placed on an
 317          * overflow page.  This calculation includes the page header, the size
 318          * of the index referencing the leaf item and the size of the leaf item
 319          * structure.  Also, don't let the user specify a minkeypage such that
 320          * a key/data pair won't fit even if both key and data are on overflow
 321          * pages.
 322          */
 323         t->bt_ovflsize = (t->bt_psize - BTDATAOFF) / b.minkeypage -
 324             (sizeof(indx_t) + NBLEAFDBT(0, 0));
 325         if (t->bt_ovflsize < NBLEAFDBT(NOVFLSIZE, NOVFLSIZE) + sizeof(indx_t))
 326                 t->bt_ovflsize =
 327                     NBLEAFDBT(NOVFLSIZE, NOVFLSIZE) + sizeof(indx_t);
 328
 329         /* Initialize the buffer pool. */
 330         if ((t->bt_mp =
 331             mpool_open(NULL, t->bt_fd, t->bt_psize, ncache)) == NULL)
 332                 goto err;
 333         if (!F_ISSET(t, B_INMEM))
 334                 mpool_filter(t->bt_mp, __bt_pgin, __bt_pgout, t);
 335
 336         /* Create a root page if new tree. */
 337         if (nroot(t) == RET_ERROR)
 338                 goto err;
 339
 340         /* Global flags. */
 341         if (dflags & DB_LOCK)
 342                 F_SET(t, B_DB_LOCK);
 343         if (dflags & DB_SHMEM)
 344                 F_SET(t, B_DB_SHMEM);
 345         if (dflags & DB_TXN)
 346                 F_SET(t, B_DB_TXN);
 347
 348         return (dbp);
 349
 350 einval: errno = EINVAL;
 351         goto err;
 352
 353 eftype: errno = EFTYPE;
 354         goto err;
 355
 356 err:    if (t) {
 357                 if (t->bt_dbp)
 358                         free(t->bt_dbp);
 359                 if (t->bt_fd != -1)
 360                         (void)close(t->bt_fd);
 361                 free(t);
 362         }
 363         return (NULL);
 364 }
 365
 366 /*
 367  * NROOT -- Create the root of a new tree.
 368  *
 369  * Parameters:
 370  *      t:      tree
 371  *
 372  * Returns:
 373  *      RET_ERROR, RET_SUCCESS
 374  */
 375 static int
 376 nroot(t)
 377         BTREE *t;
 378 {
 379         PAGE *meta, *root;
 380         pgno_t npg;
 381
 382         if ((meta = mpool_get(t->bt_mp, 0, 0)) != NULL) {
 383                 mpool_put(t->bt_mp, meta, 0);
 384                 return (RET_SUCCESS);
 385         }
 386         if (errno != EINVAL)            /* It's OK to not exist. */
 387                 return (RET_ERROR);
 388         errno = 0;
 389
 390         if ((meta = mpool_new(t->bt_mp, &npg)) == NULL)
 391                 return (RET_ERROR);
 392
 393         if ((root = mpool_new(t->bt_mp, &npg)) == NULL)
 394                 return (RET_ERROR);
 395
 396         if (npg != P_ROOT)
 397                 return (RET_ERROR);
 398         root->pgno = npg;
 399         root->prevpg = root->nextpg = P_INVALID;
 400         root->lower = BTDATAOFF;
 401         root->upper = t->bt_psize;
 402         root->flags = P_BLEAF;
 403         memset(meta, 0, t->bt_psize);
 404         mpool_put(t->bt_mp, meta, MPOOL_DIRTY);
 405         mpool_put(t->bt_mp, root, MPOOL_DIRTY);
 406         return (RET_SUCCESS);
 407 }
 408
 409 static int
 410 tmp()
 411 {
 412         sigset_t set, oset;
 413         int fd;
 414         char *envtmp = NULL;
 415         char path[MAXPATHLEN];
 416
 417         if (issetugid() == 0)
 418                 envtmp = getenv("TMPDIR");
 419         (void)snprintf(path,
 420             sizeof(path), "%s/bt.XXXXXXXXXX", envtmp ? envtmp : "/tmp");
 421
 422         (void)sigfillset(&set);
 423         (void)sigprocmask(SIG_BLOCK, &set, &oset);
 424         if ((fd = mkstemp(path)) != -1)
 425                 (void)unlink(path);
 426         (void)sigprocmask(SIG_SETMASK, &oset, NULL);
 427         return(fd);
 428 }
 429
 430 static int
 431 byteorder()
 432 {
 433         u_int32_t x;
 434         u_char *p;
 435
 436         x = 0x01020304;
 437         p = (u_char *)&x;
 438         switch (*p) {
 439         case 1:
 440                 return (BIG_ENDIAN);
 441         case 4:
 442                 return (LITTLE_ENDIAN);
 443         default:
 444                 return (0);
 445         }
 446 }
 447
 448 int
 449 __bt_fd(dbp)
 450         const DB *dbp;
 451 {
 452         BTREE *t;
 453
 454         t = dbp->internal;
 455
 456         /* Toss any page pinned across calls. */
 457         if (t->bt_pinned != NULL) {
 458                 mpool_put(t->bt_mp, t->bt_pinned, 0);
 459                 t->bt_pinned = NULL;
 460         }
 461
 462         /* In-memory database can't have a file descriptor. */
 463         if (F_ISSET(t, B_INMEM)) {
 464                 errno = ENOENT;
 465                 return (-1);
 466         }
 467         return (t->bt_fd);
 468 }