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