lib/libc/db/btree/bt_open.c

   1 /*      $NetBSD: bt_open.c,v 1.24 2008/09/11 12:58:00 joerg Exp $       */
   2
   3 /*-
   4  * Copyright (c) 1990, 1993, 1994
   5  *      The Regents of the University of California.  All rights reserved.
   6  *
   7  * This code is derived from software contributed to Berkeley by
   8  * Mike Olson.
   9  *
  10  * Redistribution and use in source and binary forms, with or without
  11  * modification, are permitted provided that the following conditions
  12  * are met:
  13  * 1. Redistributions of source code must retain the above copyright
  14  *    notice, this list of conditions and the following disclaimer.
  15  * 2. Redistributions in binary form must reproduce the above copyright
  16  *    notice, this list of conditions and the following disclaimer in the
  17  *    documentation and/or other materials provided with the distribution.
  18  * 3. Neither the name of the University nor the names of its contributors
  19  *    may be used to endorse or promote products derived from this software
  20  *    without specific prior written permission.
  21  *
  22  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
  23  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  24  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
  25  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
  26  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
  27  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
  28  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
  29  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
  30  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
  31  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  32  * SUCH DAMAGE.
  33  */
  34
  35 #if HAVE_NBTOOL_CONFIG_H
  36 #include "nbtool_config.h"
  37 #endif
  38
  39 #include <sys/cdefs.h>
  40 __RCSID("$NetBSD: bt_open.c,v 1.24 2008/09/11 12:58:00 joerg Exp $");
  41
  42 /*
  43  * Implementation of btree access method for 4.4BSD.
  44  *
  45  * The design here was originally based on that of the btree access method
  46  * used in the Postgres database system at UC Berkeley.  This implementation
  47  * is wholly independent of the Postgres code.
  48  */
  49
  50 #include "namespace.h"
  51 #include <sys/stat.h>
  52
  53 #include <assert.h>
  54 #include <errno.h>
  55 #include <fcntl.h>
  56 #include <limits.h>
  57 #include <signal.h>
  58 #include <stdio.h>
  59 #include <stdlib.h>
  60 #include <string.h>
  61 #include <unistd.h>
  62 #include <paths.h>
  63
  64 #include <db.h>
  65 #include "btree.h"
  66
  67 #ifdef DEBUG
  68 #undef  MINPSIZE
  69 #define MINPSIZE        128
  70 #endif
  71
  72 static int byteorder(void);
  73 static int nroot(BTREE *);
  74 static int tmp(void);
  75
  76 /*
  77  * __BT_OPEN -- Open a btree.
  78  *
  79  * Creates and fills a DB struct, and calls the routine that actually
  80  * opens the btree.
  81  *
  82  * Parameters:
  83  *      fname:  filename (NULL for in-memory trees)
  84  *      flags:  open flag bits
  85  *      mode:   open permission bits
  86  *      b:      BTREEINFO pointer
  87  *
  88  * Returns:
  89  *      NULL on failure, pointer to DB on success.
  90  *
  91  */
  92 DB *
  93 __bt_open(const char *fname, int flags, mode_t mode, const BTREEINFO *openinfo,
  94     int dflags)
  95 {
  96         struct stat sb;
  97         BTMETA m;
  98         BTREE *t;
  99         BTREEINFO b;
 100         DB *dbp;
 101         pgno_t ncache;
 102         ssize_t nr;
 103         size_t temp;
 104         int machine_lorder;
 105
 106         t = NULL;
 107
 108         /*
 109          * Intention is to make sure all of the user's selections are okay
 110          * here and then use them without checking.  Can't be complete, since
 111          * we don't know the right page size, lorder or flags until the backing
 112          * file is opened.  Also, the file's page size can cause the cachesize
 113          * to change.
 114          */
 115         machine_lorder = byteorder();
 116         if (openinfo) {
 117                 b = *openinfo;
 118
 119                 /* Flags: R_DUP. */
 120                 if (b.flags & ~(R_DUP))
 121                         goto einval;
 122
 123                 /*
 124                  * Page size must be indx_t aligned and >= MINPSIZE.  Default
 125                  * page size is set farther on, based on the underlying file
 126                  * transfer size.
 127                  */
 128                 if (b.psize &&
 129                     (b.psize < MINPSIZE || b.psize > MAX_PAGE_OFFSET + 1 ||
 130                     b.psize & (sizeof(indx_t) - 1)))
 131                         goto einval;
 132
 133                 /* Minimum number of keys per page; absolute minimum is 2. */
 134                 if (b.minkeypage) {
 135                         if (b.minkeypage < 2)
 136                                 goto einval;
 137                 } else
 138                         b.minkeypage = DEFMINKEYPAGE;
 139
 140                 /* If no comparison, use default comparison and prefix. */
 141                 if (b.compare == NULL) {
 142                         b.compare = __bt_defcmp;
 143                         if (b.prefix == NULL)
 144                                 b.prefix = __bt_defpfx;
 145                 }
 146
 147                 if (b.lorder == 0)
 148                         b.lorder = machine_lorder;
 149         } else {
 150                 b.compare = __bt_defcmp;
 151                 b.cachesize = 0;
 152                 b.flags = 0;
 153                 b.lorder = machine_lorder;
 154                 b.minkeypage = DEFMINKEYPAGE;
 155                 b.prefix = __bt_defpfx;
 156                 b.psize = 0;
 157         }
 158
 159         /* Check for the ubiquitous PDP-11. */
 160         if (b.lorder != BIG_ENDIAN && b.lorder != LITTLE_ENDIAN)
 161                 goto einval;
 162
 163         /* Allocate and initialize DB and BTREE structures. */
 164         if ((t = (BTREE *)malloc(sizeof(BTREE))) == NULL)
 165                 goto err;
 166         memset(t, 0, sizeof(BTREE));
 167         t->bt_fd = -1;                  /* Don't close unopened fd on error. */
 168         t->bt_lorder = b.lorder;
 169         t->bt_order = NOT;
 170         t->bt_cmp = b.compare;
 171         t->bt_pfx = b.prefix;
 172         t->bt_rfd = -1;
 173
 174         if ((t->bt_dbp = dbp = (DB *)malloc(sizeof(DB))) == NULL)
 175                 goto err;
 176         memset(t->bt_dbp, 0, sizeof(DB));
 177         if (t->bt_lorder != machine_lorder)
 178                 F_SET(t, B_NEEDSWAP);
 179
 180         dbp->type = DB_BTREE;
 181         dbp->internal = t;
 182         dbp->close = __bt_close;
 183         dbp->del = __bt_delete;
 184         dbp->fd = __bt_fd;
 185         dbp->get = __bt_get;
 186         dbp->put = __bt_put;
 187         dbp->seq = __bt_seq;
 188         dbp->sync = __bt_sync;
 189
 190         /*
 191          * If no file name was supplied, this is an in-memory btree and we
 192          * open a backing temporary file.  Otherwise, it's a disk-based tree.
 193          */
 194         if (fname) {
 195                 switch (flags & O_ACCMODE) {
 196                 case O_RDONLY:
 197                         F_SET(t, B_RDONLY);
 198                         break;
 199                 case O_RDWR:
 200                         break;
 201                 case O_WRONLY:
 202                 default:
 203                         goto einval;
 204                 }
 205
 206                 if ((t->bt_fd = open(fname, flags, mode)) == -1)
 207                         goto err;
 208                 if (fcntl(t->bt_fd, F_SETFD, FD_CLOEXEC) == -1)
 209                         goto err;
 210         } else {
 211                 if ((flags & O_ACCMODE) != O_RDWR)
 212                         goto einval;
 213                 if ((t->bt_fd = tmp()) == -1)
 214                         goto err;
 215                 F_SET(t, B_INMEM);
 216         }
 217
 218         if (fcntl(t->bt_fd, F_SETFD, FD_CLOEXEC) == -1)
 219                 goto err;
 220
 221         if (fstat(t->bt_fd, &sb))
 222                 goto err;
 223         if (sb.st_size) {
 224                 if ((nr = read(t->bt_fd, &m, sizeof(BTMETA))) < 0)
 225                         goto err;
 226                 if (nr != sizeof(BTMETA))
 227                         goto eftype;
 228
 229                 /*
 230                  * Read in the meta-data.  This can change the notion of what
 231                  * the lorder, page size and flags are, and, when the page size
 232                  * changes, the cachesize value can change too.  If the user
 233                  * specified the wrong byte order for an existing database, we
 234                  * don't bother to return an error, we just clear the NEEDSWAP
 235                  * bit.
 236                  */
 237                 if (m.magic == BTREEMAGIC)
 238                         F_CLR(t, B_NEEDSWAP);
 239                 else {
 240                         F_SET(t, B_NEEDSWAP);
 241                         M_32_SWAP(m.magic);
 242                         M_32_SWAP(m.version);
 243                         M_32_SWAP(m.psize);
 244                         M_32_SWAP(m.free);
 245                         M_32_SWAP(m.nrecs);
 246                         M_32_SWAP(m.flags);
 247                 }
 248                 if (m.magic != BTREEMAGIC || m.version != BTREEVERSION)
 249                         goto eftype;
 250                 if (m.psize < MINPSIZE || m.psize > MAX_PAGE_OFFSET + 1 ||
 251                     m.psize & (sizeof(indx_t) - 1))
 252                         goto eftype;
 253                 if (m.flags & ~SAVEMETA)
 254                         goto eftype;
 255                 b.psize = m.psize;
 256                 F_SET(t, m.flags);
 257                 t->bt_free = m.free;
 258                 t->bt_nrecs = m.nrecs;
 259         } else {
 260                 /*
 261                  * Set the page size to the best value for I/O to this file.
 262                  * Don't overflow the page offset type.
 263                  */
 264                 if (b.psize == 0) {
 265 #ifdef __minix
 266                         if (sb.st_blksize == 0) {
 267                                 /* 0 in 2 cases: upgrade from old to new struct stat or
 268                                  * there is a bug in underlying fs.
 269                                  */
 270                                 b.psize = MINIX_ST_BLKSIZE;
 271                         } else
 272 #endif
 273                                 b.psize = sb.st_blksize;
 274
 275                         if (b.psize < MINPSIZE)
 276                                 b.psize = MINPSIZE;
 277                         if (b.psize > MAX_PAGE_OFFSET + 1)
 278                                 b.psize = MAX_PAGE_OFFSET + 1;
 279                 }
 280
 281                 /* Set flag if duplicates permitted. */
 282                 if (!(b.flags & R_DUP))
 283                         F_SET(t, B_NODUPS);
 284
 285                 t->bt_free = P_INVALID;
 286                 t->bt_nrecs = 0;
 287                 F_SET(t, B_METADIRTY);
 288         }
 289
 290         t->bt_psize = b.psize;
 291
 292         /* Set the cache size; must be a multiple of the page size. */
 293         if (b.cachesize && b.cachesize & (b.psize - 1))
 294                 b.cachesize += (~b.cachesize & (b.psize - 1)) + 1;
 295         if (b.cachesize < b.psize * MINCACHE)
 296                 b.cachesize = b.psize * MINCACHE;
 297
 298         /* Calculate number of pages to cache. */
 299         ncache = (b.cachesize + t->bt_psize - 1) / t->bt_psize;
 300
 301         /*
 302          * The btree data structure requires that at least two keys can fit on
 303          * a page, but other than that there's no fixed requirement.  The user
 304          * specified a minimum number per page, and we translated that into the
 305          * number of bytes a key/data pair can use before being placed on an
 306          * overflow page.  This calculation includes the page header, the size
 307          * of the index referencing the leaf item and the size of the leaf item
 308          * structure.  Also, don't let the user specify a minkeypage such that
 309          * a key/data pair won't fit even if both key and data are on overflow
 310          * pages.
 311          */
 312         temp = (t->bt_psize - BTDATAOFF) / b.minkeypage -
 313             (sizeof(indx_t) + NBLEAFDBT(0, 0));
 314         _DBFIT(temp, indx_t);
 315         t->bt_ovflsize = (indx_t)temp;
 316         if (t->bt_ovflsize < NBLEAFDBT(NOVFLSIZE, NOVFLSIZE) + sizeof(indx_t))
 317                 t->bt_ovflsize =
 318                     NBLEAFDBT(NOVFLSIZE, NOVFLSIZE) + sizeof(indx_t);
 319
 320         /* Initialize the buffer pool. */
 321         if ((t->bt_mp =
 322             mpool_open(NULL, t->bt_fd, t->bt_psize, ncache)) == NULL)
 323                 goto err;
 324         if (!F_ISSET(t, B_INMEM))
 325                 mpool_filter(t->bt_mp, __bt_pgin, __bt_pgout, t);
 326
 327         /* Create a root page if new tree. */
 328         if (nroot(t) == RET_ERROR)
 329                 goto err;
 330
 331         /* Global flags. */
 332         if (dflags & DB_LOCK)
 333                 F_SET(t, B_DB_LOCK);
 334         if (dflags & DB_SHMEM)
 335                 F_SET(t, B_DB_SHMEM);
 336         if (dflags & DB_TXN)
 337                 F_SET(t, B_DB_TXN);
 338
 339         return (dbp);
 340
 341 einval: errno = EINVAL;
 342         goto err;
 343
 344 eftype: errno = EFTYPE;
 345         goto err;
 346
 347 err:    if (t) {
 348                 if (t->bt_dbp)
 349                         free(t->bt_dbp);
 350                 if (t->bt_fd != -1)
 351                         (void)close(t->bt_fd);
 352                 free(t);
 353         }
 354         return (NULL);
 355 }
 356
 357 /*
 358  * NROOT -- Create the root of a new tree.
 359  *
 360  * Parameters:
 361  *      t:      tree
 362  *
 363  * Returns:
 364  *      RET_ERROR, RET_SUCCESS
 365  */
 366 static int
 367 nroot(BTREE *t)
 368 {
 369         PAGE *meta, *root;
 370         pgno_t npg;
 371
 372         if ((meta = mpool_get(t->bt_mp, 0, 0)) != NULL) {
 373                 mpool_put(t->bt_mp, meta, 0);
 374                 return (RET_SUCCESS);
 375         }
 376         if (errno != EINVAL)            /* It's OK to not exist. */
 377                 return (RET_ERROR);
 378         errno = 0;
 379
 380         if ((meta = mpool_new(t->bt_mp, &npg)) == NULL)
 381                 return (RET_ERROR);
 382
 383         if ((root = mpool_new(t->bt_mp, &npg)) == NULL)
 384                 return (RET_ERROR);
 385
 386         if (npg != P_ROOT)
 387                 return (RET_ERROR);
 388         root->pgno = npg;
 389         root->prevpg = root->nextpg = P_INVALID;
 390         root->lower = BTDATAOFF;
 391         root->upper = t->bt_psize;
 392         root->flags = P_BLEAF;
 393         memset(meta, 0, t->bt_psize);
 394         mpool_put(t->bt_mp, meta, MPOOL_DIRTY);
 395         mpool_put(t->bt_mp, root, MPOOL_DIRTY);
 396         return (RET_SUCCESS);
 397 }
 398
 399 static int
 400 tmp(void)
 401 {
 402         sigset_t set, oset;
 403         size_t len;
 404         int fd;
 405         char *envtmp;
 406         char path[PATH_MAX];
 407
 408         if (issetugid())
 409                 envtmp = NULL;
 410         else
 411                 envtmp = getenv("TMPDIR");
 412
 413         len = snprintf(path,
 414             sizeof(path), "%s/bt.XXXXXX", envtmp ? envtmp : _PATH_TMP);
 415         if (len >= sizeof(path))
 416                 return -1;
 417
 418         (void)sigfillset(&set);
 419         (void)sigprocmask(SIG_BLOCK, &set, &oset);
 420         if ((fd = mkstemp(path)) != -1) {
 421                 (void)unlink(path);
 422                 (void)fcntl(fd, F_SETFD, FD_CLOEXEC);
 423         }
 424         (void)sigprocmask(SIG_SETMASK, &oset, NULL);
 425         return(fd);
 426 }
 427
 428 static int
 429 byteorder(void)
 430 {
 431         uint32_t x;
 432         uint8_t *p;
 433
 434         x = 0x01020304;
 435         p = (uint8_t *)(void *)&x;
 436         switch (*p) {
 437         case 1:
 438                 return (BIG_ENDIAN);
 439         case 4:
 440                 return (LITTLE_ENDIAN);
 441         default:
 442                 return (0);
 443         }
 444 }
 445
 446 int
 447 __bt_fd(const DB *dbp)
 448 {
 449         BTREE *t;
 450
 451         t = dbp->internal;
 452
 453         /* Toss any page pinned across calls. */
 454         if (t->bt_pinned != NULL) {
 455                 mpool_put(t->bt_mp, t->bt_pinned, 0);
 456                 t->bt_pinned = NULL;
 457         }
 458
 459         /* In-memory database can't have a file descriptor. */
 460         if (F_ISSET(t, B_INMEM)) {
 461                 errno = ENOENT;
 462                 return (-1);
 463         }
 464         return (t->bt_fd);
 465 }