1 /* $OpenBSD: bt_open.c,v 1.14 2007/09/17 07:07:23 moritz 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 /* 36 * Implementation of btree access method for 4.4BSD. 37 * 38 * The design here was originally based on that of the btree access method 39 * used in the Postgres database system at UC Berkeley. This implementation 40 * is wholly independent of the Postgres code. 41 */ 42 43 #include <sys/param.h> 44 #include <sys/stat.h> 45 46 #include <errno.h> 47 #include <fcntl.h> 48 #include <limits.h> 49 #include <signal.h> 50 #include <stdio.h> 51 #include <stdlib.h> 52 #include <string.h> 53 #include <unistd.h> 54 55 #include <db.h> 56 #include "btree.h" 57 58 #ifdef DEBUG 59 #undef MINPSIZE 60 #define MINPSIZE 128 61 #endif 62 63 static int byteorder(void); 64 static int nroot(BTREE *); 65 static int tmp(void); 66 67 /* 68 * __BT_OPEN -- Open a btree. 69 * 70 * Creates and fills a DB struct, and calls the routine that actually 71 * opens the btree. 72 * 73 * Parameters: 74 * fname: filename (NULL for in-memory trees) 75 * flags: open flag bits 76 * mode: open permission bits 77 * b: BTREEINFO pointer 78 * 79 * Returns: 80 * NULL on failure, pointer to DB on success. 81 * 82 */ 83 DB * 84 __bt_open(const char *fname, int flags, int mode, const BTREEINFO *openinfo, 85 int dflags) 86 { 87 struct stat sb; 88 BTMETA m; 89 BTREE *t; 90 BTREEINFO b; 91 DB *dbp; 92 pgno_t ncache; 93 ssize_t nr; 94 int machine_lorder, saved_errno; 95 96 t = NULL; 97 98 /* 99 * Intention is to make sure all of the user's selections are okay 100 * here and then use them without checking. Can't be complete, since 101 * we don't know the right page size, lorder or flags until the backing 102 * file is opened. Also, the file's page size can cause the cachesize 103 * to change. 104 */ 105 machine_lorder = byteorder(); 106 if (openinfo) { 107 b = *openinfo; 108 109 /* Flags: R_DUP. */ 110 if (b.flags & ~(R_DUP)) 111 goto einval; 112 113 /* 114 * Page size must be indx_t aligned and >= MINPSIZE. Default 115 * page size is set farther on, based on the underlying file 116 * transfer size. 117 */ 118 if (b.psize && 119 (b.psize < MINPSIZE || b.psize > MAX_PAGE_OFFSET + 1 || 120 b.psize & (sizeof(indx_t) - 1))) 121 goto einval; 122 123 /* Minimum number of keys per page; absolute minimum is 2. */ 124 if (b.minkeypage) { 125 if (b.minkeypage < 2) 126 goto einval; 127 } else 128 b.minkeypage = DEFMINKEYPAGE; 129 130 /* If no comparison, use default comparison and prefix. */ 131 if (b.compare == NULL) { 132 b.compare = __bt_defcmp; 133 if (b.prefix == NULL) 134 b.prefix = __bt_defpfx; 135 } 136 137 if (b.lorder == 0) 138 b.lorder = machine_lorder; 139 } else { 140 b.compare = __bt_defcmp; 141 b.cachesize = 0; 142 b.flags = 0; 143 b.lorder = machine_lorder; 144 b.minkeypage = DEFMINKEYPAGE; 145 b.prefix = __bt_defpfx; 146 b.psize = 0; 147 } 148 149 /* Check for the ubiquitous PDP-11. */ 150 if (b.lorder != BIG_ENDIAN && b.lorder != LITTLE_ENDIAN) 151 goto einval; 152 153 /* Allocate and initialize DB and BTREE structures. */ 154 if ((t = (BTREE *)malloc(sizeof(BTREE))) == NULL) 155 goto err; 156 memset(t, 0, sizeof(BTREE)); 157 t->bt_fd = -1; /* Don't close unopened fd on error. */ 158 t->bt_lorder = b.lorder; 159 t->bt_order = NOT; 160 t->bt_cmp = b.compare; 161 t->bt_pfx = b.prefix; 162 t->bt_rfd = -1; 163 164 if ((t->bt_dbp = dbp = (DB *)malloc(sizeof(DB))) == NULL) 165 goto err; 166 memset(t->bt_dbp, 0, sizeof(DB)); 167 if (t->bt_lorder != machine_lorder) 168 F_SET(t, B_NEEDSWAP); 169 170 dbp->type = DB_BTREE; 171 dbp->internal = t; 172 dbp->close = __bt_close; 173 dbp->del = __bt_delete; 174 dbp->fd = __bt_fd; 175 dbp->get = __bt_get; 176 dbp->put = __bt_put; 177 dbp->seq = __bt_seq; 178 dbp->sync = __bt_sync; 179 180 /* 181 * If no file name was supplied, this is an in-memory btree and we 182 * open a backing temporary file. Otherwise, it's a disk-based tree. 183 */ 184 if (fname) { 185 switch (flags & O_ACCMODE) { 186 case O_RDONLY: 187 F_SET(t, B_RDONLY); 188 break; 189 case O_RDWR: 190 break; 191 case O_WRONLY: 192 default: 193 goto einval; 194 } 195 196 if ((t->bt_fd = open(fname, flags, mode)) < 0) 197 goto err; 198 199 } else { 200 if ((flags & O_ACCMODE) != O_RDWR) 201 goto einval; 202 if ((t->bt_fd = tmp()) == -1) 203 goto err; 204 F_SET(t, B_INMEM); 205 } 206 207 if (fcntl(t->bt_fd, F_SETFD, 1) == -1) 208 goto err; 209 210 if (fstat(t->bt_fd, &sb)) 211 goto err; 212 if (sb.st_size) { 213 if ((nr = read(t->bt_fd, &m, sizeof(BTMETA))) < 0) 214 goto err; 215 if (nr != sizeof(BTMETA)) 216 goto eftype; 217 218 /* 219 * Read in the meta-data. This can change the notion of what 220 * the lorder, page size and flags are, and, when the page size 221 * changes, the cachesize value can change too. If the user 222 * specified the wrong byte order for an existing database, we 223 * don't bother to return an error, we just clear the NEEDSWAP 224 * bit. 225 */ 226 if (m.magic == BTREEMAGIC) 227 F_CLR(t, B_NEEDSWAP); 228 else { 229 F_SET(t, B_NEEDSWAP); 230 M_32_SWAP(m.magic); 231 M_32_SWAP(m.version); 232 M_32_SWAP(m.psize); 233 M_32_SWAP(m.free); 234 M_32_SWAP(m.nrecs); 235 M_32_SWAP(m.flags); 236 } 237 if (m.magic != BTREEMAGIC || m.version != BTREEVERSION) 238 goto eftype; 239 if (m.psize < MINPSIZE || m.psize > MAX_PAGE_OFFSET + 1 || 240 m.psize & (sizeof(indx_t) - 1)) 241 goto eftype; 242 if (m.flags & ~SAVEMETA) 243 goto eftype; 244 b.psize = m.psize; 245 F_SET(t, m.flags); 246 t->bt_free = m.free; 247 t->bt_nrecs = m.nrecs; 248 } else { 249 /* 250 * Set the page size to the best value for I/O to this file. 251 * Don't overflow the page offset type. 252 */ 253 if (b.psize == 0) { 254 b.psize = sb.st_blksize; 255 if (b.psize < MINPSIZE) 256 b.psize = MINPSIZE; 257 if (b.psize > MAX_PAGE_OFFSET + 1) 258 b.psize = MAX_PAGE_OFFSET + 1; 259 } 260 261 /* Set flag if duplicates permitted. */ 262 if (!(b.flags & R_DUP)) 263 F_SET(t, B_NODUPS); 264 265 t->bt_free = P_INVALID; 266 t->bt_nrecs = 0; 267 F_SET(t, B_METADIRTY); 268 } 269 270 t->bt_psize = b.psize; 271 272 /* Set the cache size; must be a multiple of the page size. */ 273 if (b.cachesize && b.cachesize & (b.psize - 1)) 274 b.cachesize += (~b.cachesize & (b.psize - 1)) + 1; 275 if (b.cachesize < b.psize * MINCACHE) 276 b.cachesize = b.psize * MINCACHE; 277 278 /* Calculate number of pages to cache. */ 279 ncache = (b.cachesize + t->bt_psize - 1) / t->bt_psize; 280 281 /* 282 * The btree data structure requires that at least two keys can fit on 283 * a page, but other than that there's no fixed requirement. The user 284 * specified a minimum number per page, and we translated that into the 285 * number of bytes a key/data pair can use before being placed on an 286 * overflow page. This calculation includes the page header, the size 287 * of the index referencing the leaf item and the size of the leaf item 288 * structure. Also, don't let the user specify a minkeypage such that 289 * a key/data pair won't fit even if both key and data are on overflow 290 * pages. 291 */ 292 t->bt_ovflsize = (t->bt_psize - BTDATAOFF) / b.minkeypage - 293 (sizeof(indx_t) + NBLEAFDBT(0, 0)); 294 if (t->bt_ovflsize < NBLEAFDBT(NOVFLSIZE, NOVFLSIZE) + sizeof(indx_t)) 295 t->bt_ovflsize = 296 NBLEAFDBT(NOVFLSIZE, NOVFLSIZE) + sizeof(indx_t); 297 298 /* Initialize the buffer pool. */ 299 if ((t->bt_mp = 300 mpool_open(NULL, t->bt_fd, t->bt_psize, ncache)) == NULL) 301 goto err; 302 if (!F_ISSET(t, B_INMEM)) 303 mpool_filter(t->bt_mp, __bt_pgin, __bt_pgout, t); 304 305 /* Create a root page if new tree. */ 306 if (nroot(t) == RET_ERROR) 307 goto err; 308 309 /* Global flags. */ 310 if (dflags & DB_LOCK) 311 F_SET(t, B_DB_LOCK); 312 if (dflags & DB_SHMEM) 313 F_SET(t, B_DB_SHMEM); 314 if (dflags & DB_TXN) 315 F_SET(t, B_DB_TXN); 316 317 return (dbp); 318 319 einval: errno = EINVAL; 320 goto err; 321 322 eftype: errno = EFTYPE; 323 goto err; 324 325 err: saved_errno = errno; 326 if (t) { 327 if (t->bt_dbp) 328 free(t->bt_dbp); 329 if (t->bt_fd != -1) 330 (void)close(t->bt_fd); 331 free(t); 332 } 333 errno = saved_errno; 334 return (NULL); 335 } 336 337 /* 338 * NROOT -- Create the root of a new tree. 339 * 340 * Parameters: 341 * t: tree 342 * 343 * Returns: 344 * RET_ERROR, RET_SUCCESS 345 */ 346 static int 347 nroot(BTREE *t) 348 { 349 PAGE *meta, *root; 350 pgno_t npg; 351 352 if ((root = mpool_get(t->bt_mp, 1, 0)) != NULL) { 353 if (root->lower == 0 && 354 root->pgno == 0 && 355 root->linp[0] == 0) { 356 mpool_delete(t->bt_mp, root); 357 errno = EINVAL; 358 } else { 359 mpool_put(t->bt_mp, root, 0); 360 return (RET_SUCCESS); 361 } 362 } 363 if (errno != EINVAL) /* It's OK to not exist. */ 364 return (RET_ERROR); 365 errno = 0; 366 367 if ((meta = mpool_new(t->bt_mp, &npg, MPOOL_PAGE_NEXT)) == NULL) 368 return (RET_ERROR); 369 370 if ((root = mpool_new(t->bt_mp, &npg, MPOOL_PAGE_NEXT)) == NULL) 371 return (RET_ERROR); 372 373 if (npg != P_ROOT) 374 return (RET_ERROR); 375 root->pgno = npg; 376 root->prevpg = root->nextpg = P_INVALID; 377 root->lower = BTDATAOFF; 378 root->upper = t->bt_psize; 379 root->flags = P_BLEAF; 380 memset(meta, 0, t->bt_psize); 381 mpool_put(t->bt_mp, meta, MPOOL_DIRTY); 382 mpool_put(t->bt_mp, root, MPOOL_DIRTY); 383 return (RET_SUCCESS); 384 } 385 386 static int 387 tmp(void) 388 { 389 sigset_t set, oset; 390 int fd, len; 391 char *envtmp = NULL; 392 char path[MAXPATHLEN]; 393 394 if (issetugid() == 0) 395 envtmp = getenv("TMPDIR"); 396 len = snprintf(path, 397 sizeof(path), "%s/bt.XXXXXX", envtmp ? envtmp : "/tmp"); 398 if (len < 0 || len >= sizeof(path)) { 399 errno = ENAMETOOLONG; 400 return(-1); 401 } 402 403 (void)sigfillset(&set); 404 (void)sigprocmask(SIG_BLOCK, &set, &oset); 405 if ((fd = mkstemp(path)) != -1) 406 (void)unlink(path); 407 (void)sigprocmask(SIG_SETMASK, &oset, NULL); 408 return(fd); 409 } 410 411 static int 412 byteorder(void) 413 { 414 u_int32_t x; 415 u_char *p; 416 417 x = 0x01020304; 418 p = (u_char *)&x; 419 switch (*p) { 420 case 1: 421 return (BIG_ENDIAN); 422 case 4: 423 return (LITTLE_ENDIAN); 424 default: 425 return (0); 426 } 427 } 428 429 int 430 __bt_fd(const DB *dbp) 431 { 432 BTREE *t; 433 434 t = dbp->internal; 435 436 /* Toss any page pinned across calls. */ 437 if (t->bt_pinned != NULL) { 438 mpool_put(t->bt_mp, t->bt_pinned, 0); 439 t->bt_pinned = NULL; 440 } 441 442 /* In-memory database can't have a file descriptor. */ 443 if (F_ISSET(t, B_INMEM)) { 444 errno = ENOENT; 445 return (-1); 446 } 447 return (t->bt_fd); 448 } 449