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 b.psize = sb.st_blksize; 266 if (b.psize < MINPSIZE) 267 b.psize = MINPSIZE; 268 if (b.psize > MAX_PAGE_OFFSET + 1) 269 b.psize = MAX_PAGE_OFFSET + 1; 270 } 271 272 /* Set flag if duplicates permitted. */ 273 if (!(b.flags & R_DUP)) 274 F_SET(t, B_NODUPS); 275 276 t->bt_free = P_INVALID; 277 t->bt_nrecs = 0; 278 F_SET(t, B_METADIRTY); 279 } 280 281 t->bt_psize = b.psize; 282 283 /* Set the cache size; must be a multiple of the page size. */ 284 if (b.cachesize && b.cachesize & (b.psize - 1)) 285 b.cachesize += (~b.cachesize & (b.psize - 1)) + 1; 286 if (b.cachesize < b.psize * MINCACHE) 287 b.cachesize = b.psize * MINCACHE; 288 289 /* Calculate number of pages to cache. */ 290 ncache = (b.cachesize + t->bt_psize - 1) / t->bt_psize; 291 292 /* 293 * The btree data structure requires that at least two keys can fit on 294 * a page, but other than that there's no fixed requirement. The user 295 * specified a minimum number per page, and we translated that into the 296 * number of bytes a key/data pair can use before being placed on an 297 * overflow page. This calculation includes the page header, the size 298 * of the index referencing the leaf item and the size of the leaf item 299 * structure. Also, don't let the user specify a minkeypage such that 300 * a key/data pair won't fit even if both key and data are on overflow 301 * pages. 302 */ 303 temp = (t->bt_psize - BTDATAOFF) / b.minkeypage - 304 (sizeof(indx_t) + NBLEAFDBT(0, 0)); 305 _DBFIT(temp, indx_t); 306 t->bt_ovflsize = (indx_t)temp; 307 if (t->bt_ovflsize < NBLEAFDBT(NOVFLSIZE, NOVFLSIZE) + sizeof(indx_t)) 308 t->bt_ovflsize = 309 NBLEAFDBT(NOVFLSIZE, NOVFLSIZE) + sizeof(indx_t); 310 311 /* Initialize the buffer pool. */ 312 if ((t->bt_mp = 313 mpool_open(NULL, t->bt_fd, t->bt_psize, ncache)) == NULL) 314 goto err; 315 if (!F_ISSET(t, B_INMEM)) 316 mpool_filter(t->bt_mp, __bt_pgin, __bt_pgout, t); 317 318 /* Create a root page if new tree. */ 319 if (nroot(t) == RET_ERROR) 320 goto err; 321 322 /* Global flags. */ 323 if (dflags & DB_LOCK) 324 F_SET(t, B_DB_LOCK); 325 if (dflags & DB_SHMEM) 326 F_SET(t, B_DB_SHMEM); 327 if (dflags & DB_TXN) 328 F_SET(t, B_DB_TXN); 329 330 return (dbp); 331 332 einval: errno = EINVAL; 333 goto err; 334 335 eftype: errno = EFTYPE; 336 goto err; 337 338 err: if (t) { 339 if (t->bt_dbp) 340 free(t->bt_dbp); 341 if (t->bt_fd != -1) 342 (void)close(t->bt_fd); 343 free(t); 344 } 345 return (NULL); 346 } 347 348 /* 349 * NROOT -- Create the root of a new tree. 350 * 351 * Parameters: 352 * t: tree 353 * 354 * Returns: 355 * RET_ERROR, RET_SUCCESS 356 */ 357 static int 358 nroot(BTREE *t) 359 { 360 PAGE *meta, *root; 361 pgno_t npg; 362 363 if ((meta = mpool_get(t->bt_mp, 0, 0)) != NULL) { 364 mpool_put(t->bt_mp, meta, 0); 365 return (RET_SUCCESS); 366 } 367 if (errno != EINVAL) /* It's OK to not exist. */ 368 return (RET_ERROR); 369 errno = 0; 370 371 if ((meta = mpool_new(t->bt_mp, &npg)) == NULL) 372 return (RET_ERROR); 373 374 if ((root = mpool_new(t->bt_mp, &npg)) == NULL) 375 return (RET_ERROR); 376 377 if (npg != P_ROOT) 378 return (RET_ERROR); 379 root->pgno = npg; 380 root->prevpg = root->nextpg = P_INVALID; 381 root->lower = BTDATAOFF; 382 root->upper = t->bt_psize; 383 root->flags = P_BLEAF; 384 memset(meta, 0, t->bt_psize); 385 mpool_put(t->bt_mp, meta, MPOOL_DIRTY); 386 mpool_put(t->bt_mp, root, MPOOL_DIRTY); 387 return (RET_SUCCESS); 388 } 389 390 static int 391 tmp(void) 392 { 393 sigset_t set, oset; 394 size_t len; 395 int fd; 396 char *envtmp; 397 char path[PATH_MAX]; 398 399 if (issetugid()) 400 envtmp = NULL; 401 else 402 envtmp = getenv("TMPDIR"); 403 404 len = snprintf(path, 405 sizeof(path), "%s/bt.XXXXXX", envtmp ? envtmp : _PATH_TMP); 406 if (len >= sizeof(path)) 407 return -1; 408 409 (void)sigfillset(&set); 410 (void)sigprocmask(SIG_BLOCK, &set, &oset); 411 if ((fd = mkstemp(path)) != -1) { 412 (void)unlink(path); 413 (void)fcntl(fd, F_SETFD, FD_CLOEXEC); 414 } 415 (void)sigprocmask(SIG_SETMASK, &oset, NULL); 416 return(fd); 417 } 418 419 static int 420 byteorder(void) 421 { 422 uint32_t x; 423 uint8_t *p; 424 425 x = 0x01020304; 426 p = (uint8_t *)(void *)&x; 427 switch (*p) { 428 case 1: 429 return (BIG_ENDIAN); 430 case 4: 431 return (LITTLE_ENDIAN); 432 default: 433 return (0); 434 } 435 } 436 437 int 438 __bt_fd(const DB *dbp) 439 { 440 BTREE *t; 441 442 t = dbp->internal; 443 444 /* Toss any page pinned across calls. */ 445 if (t->bt_pinned != NULL) { 446 mpool_put(t->bt_mp, t->bt_pinned, 0); 447 t->bt_pinned = NULL; 448 } 449 450 /* In-memory database can't have a file descriptor. */ 451 if (F_ISSET(t, B_INMEM)) { 452 errno = ENOENT; 453 return (-1); 454 } 455 return (t->bt_fd); 456 } 457