1 /* $OpenBSD: bt_open.c,v 1.11 2003/06/02 20:18:33 millert 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 defined(LIBC_SCCS) && !defined(lint) 36 #if 0 37 static char sccsid[] = "@(#)bt_open.c 8.11 (Berkeley) 11/2/95"; 38 #else 39 static const char rcsid[] = "$OpenBSD: bt_open.c,v 1.11 2003/06/02 20:18:33 millert Exp $"; 40 #endif 41 #endif /* LIBC_SCCS and not lint */ 42 43 /* 44 * Implementation of btree access method for 4.4BSD. 45 * 46 * The design here was originally based on that of the btree access method 47 * used in the Postgres database system at UC Berkeley. This implementation 48 * is wholly independent of the Postgres code. 49 */ 50 51 #include <sys/param.h> 52 #include <sys/stat.h> 53 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 63 #include <db.h> 64 #include "btree.h" 65 66 #ifdef DEBUG 67 #undef MINPSIZE 68 #define MINPSIZE 128 69 #endif 70 71 static int byteorder(void); 72 static int nroot(BTREE *); 73 static int tmp(void); 74 75 /* 76 * __BT_OPEN -- Open a btree. 77 * 78 * Creates and fills a DB struct, and calls the routine that actually 79 * opens the btree. 80 * 81 * Parameters: 82 * fname: filename (NULL for in-memory trees) 83 * flags: open flag bits 84 * mode: open permission bits 85 * b: BTREEINFO pointer 86 * 87 * Returns: 88 * NULL on failure, pointer to DB on success. 89 * 90 */ 91 DB * 92 __bt_open(fname, flags, mode, openinfo, dflags) 93 const char *fname; 94 int flags, mode, dflags; 95 const BTREEINFO *openinfo; 96 { 97 struct stat sb; 98 BTMETA m; 99 BTREE *t; 100 BTREEINFO b; 101 DB *dbp; 102 pgno_t ncache; 103 ssize_t nr; 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)) < 0) 207 goto err; 208 209 } else { 210 if ((flags & O_ACCMODE) != O_RDWR) 211 goto einval; 212 if ((t->bt_fd = tmp()) == -1) 213 goto err; 214 F_SET(t, B_INMEM); 215 } 216 217 if (fcntl(t->bt_fd, F_SETFD, 1) == -1) 218 goto err; 219 220 if (fstat(t->bt_fd, &sb)) 221 goto err; 222 if (sb.st_size) { 223 if ((nr = read(t->bt_fd, &m, sizeof(BTMETA))) < 0) 224 goto err; 225 if (nr != sizeof(BTMETA)) 226 goto eftype; 227 228 /* 229 * Read in the meta-data. This can change the notion of what 230 * the lorder, page size and flags are, and, when the page size 231 * changes, the cachesize value can change too. If the user 232 * specified the wrong byte order for an existing database, we 233 * don't bother to return an error, we just clear the NEEDSWAP 234 * bit. 235 */ 236 if (m.magic == BTREEMAGIC) 237 F_CLR(t, B_NEEDSWAP); 238 else { 239 F_SET(t, B_NEEDSWAP); 240 M_32_SWAP(m.magic); 241 M_32_SWAP(m.version); 242 M_32_SWAP(m.psize); 243 M_32_SWAP(m.free); 244 M_32_SWAP(m.nrecs); 245 M_32_SWAP(m.flags); 246 } 247 if (m.magic != BTREEMAGIC || m.version != BTREEVERSION) 248 goto eftype; 249 if (m.psize < MINPSIZE || m.psize > MAX_PAGE_OFFSET + 1 || 250 m.psize & (sizeof(indx_t) - 1)) 251 goto eftype; 252 if (m.flags & ~SAVEMETA) 253 goto eftype; 254 b.psize = m.psize; 255 F_SET(t, m.flags); 256 t->bt_free = m.free; 257 t->bt_nrecs = m.nrecs; 258 } else { 259 /* 260 * Set the page size to the best value for I/O to this file. 261 * Don't overflow the page offset type. 262 */ 263 if (b.psize == 0) { 264 b.psize = sb.st_blksize; 265 if (b.psize < MINPSIZE) 266 b.psize = MINPSIZE; 267 if (b.psize > MAX_PAGE_OFFSET + 1) 268 b.psize = MAX_PAGE_OFFSET + 1; 269 } 270 271 /* Set flag if duplicates permitted. */ 272 if (!(b.flags & R_DUP)) 273 F_SET(t, B_NODUPS); 274 275 t->bt_free = P_INVALID; 276 t->bt_nrecs = 0; 277 F_SET(t, B_METADIRTY); 278 } 279 280 t->bt_psize = b.psize; 281 282 /* Set the cache size; must be a multiple of the page size. */ 283 if (b.cachesize && b.cachesize & (b.psize - 1)) 284 b.cachesize += (~b.cachesize & (b.psize - 1)) + 1; 285 if (b.cachesize < b.psize * MINCACHE) 286 b.cachesize = b.psize * MINCACHE; 287 288 /* Calculate number of pages to cache. */ 289 ncache = (b.cachesize + t->bt_psize - 1) / t->bt_psize; 290 291 /* 292 * The btree data structure requires that at least two keys can fit on 293 * a page, but other than that there's no fixed requirement. The user 294 * specified a minimum number per page, and we translated that into the 295 * number of bytes a key/data pair can use before being placed on an 296 * overflow page. This calculation includes the page header, the size 297 * of the index referencing the leaf item and the size of the leaf item 298 * structure. Also, don't let the user specify a minkeypage such that 299 * a key/data pair won't fit even if both key and data are on overflow 300 * pages. 301 */ 302 t->bt_ovflsize = (t->bt_psize - BTDATAOFF) / b.minkeypage - 303 (sizeof(indx_t) + NBLEAFDBT(0, 0)); 304 if (t->bt_ovflsize < NBLEAFDBT(NOVFLSIZE, NOVFLSIZE) + sizeof(indx_t)) 305 t->bt_ovflsize = 306 NBLEAFDBT(NOVFLSIZE, NOVFLSIZE) + sizeof(indx_t); 307 308 /* Initialize the buffer pool. */ 309 if ((t->bt_mp = 310 mpool_open(NULL, t->bt_fd, t->bt_psize, ncache)) == NULL) 311 goto err; 312 if (!F_ISSET(t, B_INMEM)) 313 mpool_filter(t->bt_mp, __bt_pgin, __bt_pgout, t); 314 315 /* Create a root page if new tree. */ 316 if (nroot(t) == RET_ERROR) 317 goto err; 318 319 /* Global flags. */ 320 if (dflags & DB_LOCK) 321 F_SET(t, B_DB_LOCK); 322 if (dflags & DB_SHMEM) 323 F_SET(t, B_DB_SHMEM); 324 if (dflags & DB_TXN) 325 F_SET(t, B_DB_TXN); 326 327 return (dbp); 328 329 einval: errno = EINVAL; 330 goto err; 331 332 eftype: errno = EFTYPE; 333 goto err; 334 335 err: if (t) { 336 if (t->bt_dbp) 337 free(t->bt_dbp); 338 if (t->bt_fd != -1) 339 (void)close(t->bt_fd); 340 free(t); 341 } 342 return (NULL); 343 } 344 345 /* 346 * NROOT -- Create the root of a new tree. 347 * 348 * Parameters: 349 * t: tree 350 * 351 * Returns: 352 * RET_ERROR, RET_SUCCESS 353 */ 354 static int 355 nroot(t) 356 BTREE *t; 357 { 358 PAGE *meta, *root; 359 pgno_t npg; 360 361 if ((root = mpool_get(t->bt_mp, 1, 0)) != NULL) { 362 if (root->lower == 0 && 363 root->pgno == 0 && 364 root->linp[0] == 0) { 365 mpool_delete(t->bt_mp, root); 366 errno = EINVAL; 367 } else { 368 mpool_put(t->bt_mp, root, 0); 369 return (RET_SUCCESS); 370 } 371 } 372 if (errno != EINVAL) /* It's OK to not exist. */ 373 return (RET_ERROR); 374 errno = 0; 375 376 if ((meta = mpool_new(t->bt_mp, &npg, MPOOL_PAGE_NEXT)) == NULL) 377 return (RET_ERROR); 378 379 if ((root = mpool_new(t->bt_mp, &npg, MPOOL_PAGE_NEXT)) == NULL) 380 return (RET_ERROR); 381 382 if (npg != P_ROOT) 383 return (RET_ERROR); 384 root->pgno = npg; 385 root->prevpg = root->nextpg = P_INVALID; 386 root->lower = BTDATAOFF; 387 root->upper = t->bt_psize; 388 root->flags = P_BLEAF; 389 memset(meta, 0, t->bt_psize); 390 mpool_put(t->bt_mp, meta, MPOOL_DIRTY); 391 mpool_put(t->bt_mp, root, MPOOL_DIRTY); 392 return (RET_SUCCESS); 393 } 394 395 static int 396 tmp() 397 { 398 sigset_t set, oset; 399 int fd; 400 char *envtmp = NULL; 401 char path[MAXPATHLEN]; 402 403 if (issetugid() == 0) 404 envtmp = getenv("TMPDIR"); 405 (void)snprintf(path, 406 sizeof(path), "%s/bt.XXXXXX", envtmp ? envtmp : "/tmp"); 407 408 (void)sigfillset(&set); 409 (void)sigprocmask(SIG_BLOCK, &set, &oset); 410 if ((fd = mkstemp(path)) != -1) 411 (void)unlink(path); 412 (void)sigprocmask(SIG_SETMASK, &oset, NULL); 413 return(fd); 414 } 415 416 static int 417 byteorder() 418 { 419 u_int32_t x; 420 u_char *p; 421 422 x = 0x01020304; 423 p = (u_char *)&x; 424 switch (*p) { 425 case 1: 426 return (BIG_ENDIAN); 427 case 4: 428 return (LITTLE_ENDIAN); 429 default: 430 return (0); 431 } 432 } 433 434 int 435 __bt_fd(dbp) 436 const DB *dbp; 437 { 438 BTREE *t; 439 440 t = dbp->internal; 441 442 /* Toss any page pinned across calls. */ 443 if (t->bt_pinned != NULL) { 444 mpool_put(t->bt_mp, t->bt_pinned, 0); 445 t->bt_pinned = NULL; 446 } 447 448 /* In-memory database can't have a file descriptor. */ 449 if (F_ISSET(t, B_INMEM)) { 450 errno = ENOENT; 451 return (-1); 452 } 453 return (t->bt_fd); 454 } 455