1 /* $NetBSD: bt_open.c,v 1.21 2007/02/03 23:46:09 christos 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 #include <sys/cdefs.h> 36 #if defined(LIBC_SCCS) && !defined(lint) 37 #if 0 38 static char sccsid[] = "@(#)bt_open.c 8.10 (Berkeley) 8/17/94"; 39 #else 40 __RCSID("$NetBSD: bt_open.c,v 1.21 2007/02/03 23:46:09 christos Exp $"); 41 #endif 42 #endif /* LIBC_SCCS and not lint */ 43 44 /* 45 * Implementation of btree access method for 4.4BSD. 46 * 47 * The design here was originally based on that of the btree access method 48 * used in the Postgres database system at UC Berkeley. This implementation 49 * is wholly independent of the Postgres code. 50 */ 51 52 #include "namespace.h" 53 #include <sys/stat.h> 54 55 #include <assert.h> 56 #include <errno.h> 57 #include <fcntl.h> 58 #include <limits.h> 59 #include <signal.h> 60 #include <stdio.h> 61 #include <stdlib.h> 62 #include <string.h> 63 #include <unistd.h> 64 #include <paths.h> 65 66 #include <db.h> 67 #include "btree.h" 68 69 #ifdef DEBUG 70 #undef MINPSIZE 71 #define MINPSIZE 128 72 #endif 73 74 static int byteorder(void); 75 static int nroot(BTREE *); 76 static int tmp(void); 77 78 /* 79 * __BT_OPEN -- Open a btree. 80 * 81 * Creates and fills a DB struct, and calls the routine that actually 82 * opens the btree. 83 * 84 * Parameters: 85 * fname: filename (NULL for in-memory trees) 86 * flags: open flag bits 87 * mode: open permission bits 88 * b: BTREEINFO pointer 89 * 90 * Returns: 91 * NULL on failure, pointer to DB on success. 92 * 93 */ 94 DB * 95 __bt_open(const char *fname, int flags, mode_t mode, const BTREEINFO *openinfo, 96 int dflags) 97 { 98 struct stat sb; 99 BTMETA m; 100 BTREE *t; 101 BTREEINFO b; 102 DB *dbp; 103 pgno_t ncache; 104 ssize_t nr; 105 size_t temp; 106 int machine_lorder; 107 108 t = NULL; 109 110 /* 111 * Intention is to make sure all of the user's selections are okay 112 * here and then use them without checking. Can't be complete, since 113 * we don't know the right page size, lorder or flags until the backing 114 * file is opened. Also, the file's page size can cause the cachesize 115 * to change. 116 */ 117 machine_lorder = byteorder(); 118 if (openinfo) { 119 b = *openinfo; 120 121 /* Flags: R_DUP. */ 122 if (b.flags & ~(R_DUP)) 123 goto einval; 124 125 /* 126 * Page size must be indx_t aligned and >= MINPSIZE. Default 127 * page size is set farther on, based on the underlying file 128 * transfer size. 129 */ 130 if (b.psize && 131 (b.psize < MINPSIZE || b.psize > MAX_PAGE_OFFSET + 1 || 132 b.psize & (sizeof(indx_t) - 1))) 133 goto einval; 134 135 /* Minimum number of keys per page; absolute minimum is 2. */ 136 if (b.minkeypage) { 137 if (b.minkeypage < 2) 138 goto einval; 139 } else 140 b.minkeypage = DEFMINKEYPAGE; 141 142 /* If no comparison, use default comparison and prefix. */ 143 if (b.compare == NULL) { 144 b.compare = __bt_defcmp; 145 if (b.prefix == NULL) 146 b.prefix = __bt_defpfx; 147 } 148 149 if (b.lorder == 0) 150 b.lorder = machine_lorder; 151 } else { 152 b.compare = __bt_defcmp; 153 b.cachesize = 0; 154 b.flags = 0; 155 b.lorder = machine_lorder; 156 b.minkeypage = DEFMINKEYPAGE; 157 b.prefix = __bt_defpfx; 158 b.psize = 0; 159 } 160 161 /* Check for the ubiquitous PDP-11. */ 162 if (b.lorder != BIG_ENDIAN && b.lorder != LITTLE_ENDIAN) 163 goto einval; 164 165 /* Allocate and initialize DB and BTREE structures. */ 166 if ((t = (BTREE *)malloc(sizeof(BTREE))) == NULL) 167 goto err; 168 memset(t, 0, sizeof(BTREE)); 169 t->bt_fd = -1; /* Don't close unopened fd on error. */ 170 t->bt_lorder = b.lorder; 171 t->bt_order = NOT; 172 t->bt_cmp = b.compare; 173 t->bt_pfx = b.prefix; 174 t->bt_rfd = -1; 175 176 if ((t->bt_dbp = dbp = (DB *)malloc(sizeof(DB))) == NULL) 177 goto err; 178 memset(t->bt_dbp, 0, sizeof(DB)); 179 if (t->bt_lorder != machine_lorder) 180 F_SET(t, B_NEEDSWAP); 181 182 dbp->type = DB_BTREE; 183 dbp->internal = t; 184 dbp->close = __bt_close; 185 dbp->del = __bt_delete; 186 dbp->fd = __bt_fd; 187 dbp->get = __bt_get; 188 dbp->put = __bt_put; 189 dbp->seq = __bt_seq; 190 dbp->sync = __bt_sync; 191 192 /* 193 * If no file name was supplied, this is an in-memory btree and we 194 * open a backing temporary file. Otherwise, it's a disk-based tree. 195 */ 196 if (fname) { 197 switch (flags & O_ACCMODE) { 198 case O_RDONLY: 199 F_SET(t, B_RDONLY); 200 break; 201 case O_RDWR: 202 break; 203 case O_WRONLY: 204 default: 205 goto einval; 206 } 207 208 if ((t->bt_fd = open(fname, flags, mode)) == -1) 209 goto err; 210 if (fcntl(t->bt_fd, F_SETFD, FD_CLOEXEC) == -1) 211 goto err; 212 } else { 213 if ((flags & O_ACCMODE) != O_RDWR) 214 goto einval; 215 if ((t->bt_fd = tmp()) == -1) 216 goto err; 217 F_SET(t, B_INMEM); 218 } 219 220 if (fcntl(t->bt_fd, F_SETFD, FD_CLOEXEC) == -1) 221 goto err; 222 223 if (fstat(t->bt_fd, &sb)) 224 goto err; 225 if (sb.st_size) { 226 if ((nr = read(t->bt_fd, &m, sizeof(BTMETA))) < 0) 227 goto err; 228 if (nr != sizeof(BTMETA)) 229 goto eftype; 230 231 /* 232 * Read in the meta-data. This can change the notion of what 233 * the lorder, page size and flags are, and, when the page size 234 * changes, the cachesize value can change too. If the user 235 * specified the wrong byte order for an existing database, we 236 * don't bother to return an error, we just clear the NEEDSWAP 237 * bit. 238 */ 239 if (m.magic == BTREEMAGIC) 240 F_CLR(t, B_NEEDSWAP); 241 else { 242 F_SET(t, B_NEEDSWAP); 243 M_32_SWAP(m.magic); 244 M_32_SWAP(m.version); 245 M_32_SWAP(m.psize); 246 M_32_SWAP(m.free); 247 M_32_SWAP(m.nrecs); 248 M_32_SWAP(m.flags); 249 } 250 if (m.magic != BTREEMAGIC || m.version != BTREEVERSION) 251 goto eftype; 252 if (m.psize < MINPSIZE || m.psize > MAX_PAGE_OFFSET + 1 || 253 m.psize & (sizeof(indx_t) - 1)) 254 goto eftype; 255 if (m.flags & ~SAVEMETA) 256 goto eftype; 257 b.psize = m.psize; 258 F_SET(t, m.flags); 259 t->bt_free = m.free; 260 t->bt_nrecs = m.nrecs; 261 } else { 262 /* 263 * Set the page size to the best value for I/O to this file. 264 * Don't overflow the page offset type. 265 */ 266 if (b.psize == 0) { 267 b.psize = sb.st_blksize; 268 if (b.psize < MINPSIZE) 269 b.psize = MINPSIZE; 270 if (b.psize > MAX_PAGE_OFFSET + 1) 271 b.psize = MAX_PAGE_OFFSET + 1; 272 } 273 274 /* Set flag if duplicates permitted. */ 275 if (!(b.flags & R_DUP)) 276 F_SET(t, B_NODUPS); 277 278 t->bt_free = P_INVALID; 279 t->bt_nrecs = 0; 280 F_SET(t, B_METADIRTY); 281 } 282 283 t->bt_psize = b.psize; 284 285 /* Set the cache size; must be a multiple of the page size. */ 286 if (b.cachesize && b.cachesize & (b.psize - 1)) 287 b.cachesize += (~b.cachesize & (b.psize - 1)) + 1; 288 if (b.cachesize < b.psize * MINCACHE) 289 b.cachesize = b.psize * MINCACHE; 290 291 /* Calculate number of pages to cache. */ 292 ncache = (b.cachesize + t->bt_psize - 1) / t->bt_psize; 293 294 /* 295 * The btree data structure requires that at least two keys can fit on 296 * a page, but other than that there's no fixed requirement. The user 297 * specified a minimum number per page, and we translated that into the 298 * number of bytes a key/data pair can use before being placed on an 299 * overflow page. This calculation includes the page header, the size 300 * of the index referencing the leaf item and the size of the leaf item 301 * structure. Also, don't let the user specify a minkeypage such that 302 * a key/data pair won't fit even if both key and data are on overflow 303 * pages. 304 */ 305 temp = (t->bt_psize - BTDATAOFF) / b.minkeypage - 306 (sizeof(indx_t) + NBLEAFDBT(0, 0)); 307 _DBFIT(temp, indx_t); 308 t->bt_ovflsize = (indx_t)temp; 309 if (t->bt_ovflsize < NBLEAFDBT(NOVFLSIZE, NOVFLSIZE) + sizeof(indx_t)) 310 t->bt_ovflsize = 311 NBLEAFDBT(NOVFLSIZE, NOVFLSIZE) + sizeof(indx_t); 312 313 /* Initialize the buffer pool. */ 314 if ((t->bt_mp = 315 mpool_open(NULL, t->bt_fd, t->bt_psize, ncache)) == NULL) 316 goto err; 317 if (!F_ISSET(t, B_INMEM)) 318 mpool_filter(t->bt_mp, __bt_pgin, __bt_pgout, t); 319 320 /* Create a root page if new tree. */ 321 if (nroot(t) == RET_ERROR) 322 goto err; 323 324 /* Global flags. */ 325 if (dflags & DB_LOCK) 326 F_SET(t, B_DB_LOCK); 327 if (dflags & DB_SHMEM) 328 F_SET(t, B_DB_SHMEM); 329 if (dflags & DB_TXN) 330 F_SET(t, B_DB_TXN); 331 332 return (dbp); 333 334 einval: errno = EINVAL; 335 goto err; 336 337 eftype: errno = EFTYPE; 338 goto err; 339 340 err: if (t) { 341 if (t->bt_dbp) 342 free(t->bt_dbp); 343 if (t->bt_fd != -1) 344 (void)close(t->bt_fd); 345 free(t); 346 } 347 return (NULL); 348 } 349 350 /* 351 * NROOT -- Create the root of a new tree. 352 * 353 * Parameters: 354 * t: tree 355 * 356 * Returns: 357 * RET_ERROR, RET_SUCCESS 358 */ 359 static int 360 nroot(BTREE *t) 361 { 362 PAGE *meta, *root; 363 pgno_t npg; 364 365 if ((meta = mpool_get(t->bt_mp, 0, 0)) != NULL) { 366 mpool_put(t->bt_mp, meta, 0); 367 return (RET_SUCCESS); 368 } 369 if (errno != EINVAL) /* It's OK to not exist. */ 370 return (RET_ERROR); 371 errno = 0; 372 373 if ((meta = mpool_new(t->bt_mp, &npg)) == NULL) 374 return (RET_ERROR); 375 376 if ((root = mpool_new(t->bt_mp, &npg)) == NULL) 377 return (RET_ERROR); 378 379 if (npg != P_ROOT) 380 return (RET_ERROR); 381 root->pgno = npg; 382 root->prevpg = root->nextpg = P_INVALID; 383 root->lower = BTDATAOFF; 384 root->upper = t->bt_psize; 385 root->flags = P_BLEAF; 386 memset(meta, 0, t->bt_psize); 387 mpool_put(t->bt_mp, meta, MPOOL_DIRTY); 388 mpool_put(t->bt_mp, root, MPOOL_DIRTY); 389 return (RET_SUCCESS); 390 } 391 392 static int 393 tmp(void) 394 { 395 sigset_t set, oset; 396 size_t len; 397 int fd; 398 char *envtmp; 399 char path[PATH_MAX]; 400 401 if (issetugid()) 402 envtmp = NULL; 403 else 404 envtmp = getenv("TMPDIR"); 405 406 len = snprintf(path, 407 sizeof(path), "%s/bt.XXXXXX", envtmp ? envtmp : _PATH_TMP); 408 if (len >= sizeof(path)) 409 return -1; 410 411 (void)sigfillset(&set); 412 (void)sigprocmask(SIG_BLOCK, &set, &oset); 413 if ((fd = mkstemp(path)) != -1) { 414 (void)unlink(path); 415 (void)fcntl(fd, F_SETFD, FD_CLOEXEC); 416 } 417 (void)sigprocmask(SIG_SETMASK, &oset, NULL); 418 return(fd); 419 } 420 421 static int 422 byteorder(void) 423 { 424 u_int32_t x; 425 u_char *p; 426 427 x = 0x01020304; 428 p = (u_char *)(void *)&x; 429 switch (*p) { 430 case 1: 431 return (BIG_ENDIAN); 432 case 4: 433 return (LITTLE_ENDIAN); 434 default: 435 return (0); 436 } 437 } 438 439 int 440 __bt_fd(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 (F_ISSET(t, B_INMEM)) { 454 errno = ENOENT; 455 return (-1); 456 } 457 return (t->bt_fd); 458 } 459