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 * 3. 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 * $FreeBSD: src/lib/libc/db/btree/bt_open.c,v 1.7.2.1 2000/11/02 10:30:07 kris Exp $ 33 * $DragonFly: src/lib/libc/db/btree/bt_open.c,v 1.6 2005/11/12 23:01:54 swildner Exp $ 34 * 35 * @(#)bt_open.c 8.10 (Berkeley) 8/17/94 36 */ 37 38 /* 39 * Implementation of btree access method for 4.4BSD. 40 * 41 * The design here was originally based on that of the btree access method 42 * used in the Postgres database system at UC Berkeley. This implementation 43 * is wholly independent of the Postgres code. 44 */ 45 46 #include "namespace.h" 47 #include <sys/param.h> 48 #include <sys/stat.h> 49 50 #include <errno.h> 51 #include <fcntl.h> 52 #include <limits.h> 53 #include <signal.h> 54 #include <stdio.h> 55 #include <stdlib.h> 56 #include <string.h> 57 #include <unistd.h> 58 #include "un-namespace.h" 59 60 #include <db.h> 61 #include "btree.h" 62 63 #ifdef DEBUG 64 #undef MINPSIZE 65 #define MINPSIZE 128 66 #endif 67 68 static int byteorder (void); 69 static int nroot (BTREE *); 70 static int tmp (void); 71 72 /* 73 * __BT_OPEN -- Open a btree. 74 * 75 * Creates and fills a DB struct, and calls the routine that actually 76 * opens the btree. 77 * 78 * Parameters: 79 * fname: filename (NULL for in-memory trees) 80 * flags: open flag bits 81 * mode: open permission bits 82 * b: BTREEINFO pointer 83 * 84 * Returns: 85 * NULL on failure, pointer to DB on success. 86 * 87 */ 88 DB * 89 __bt_open(const char *fname, int flags, int mode, const BTREEINFO *openinfo, 90 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; 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 *)malloc(sizeof(BTREE))) == NULL) 160 goto err; 161 memset(t, 0, sizeof(BTREE)); 162 t->bt_fd = -1; /* Don't close unopened fd on error. */ 163 t->bt_lorder = b.lorder; 164 t->bt_order = NOT; 165 t->bt_cmp = b.compare; 166 t->bt_pfx = b.prefix; 167 t->bt_rfd = -1; 168 169 if ((t->bt_dbp = dbp = (DB *)malloc(sizeof(DB))) == NULL) 170 goto err; 171 memset(t->bt_dbp, 0, sizeof(DB)); 172 if (t->bt_lorder != machine_lorder) 173 F_SET(t, B_NEEDSWAP); 174 175 dbp->type = DB_BTREE; 176 dbp->internal = t; 177 dbp->close = __bt_close; 178 dbp->del = __bt_delete; 179 dbp->fd = __bt_fd; 180 dbp->get = __bt_get; 181 dbp->put = __bt_put; 182 dbp->seq = __bt_seq; 183 dbp->sync = __bt_sync; 184 185 /* 186 * If no file name was supplied, this is an in-memory btree and we 187 * open a backing temporary file. Otherwise, it's a disk-based tree. 188 */ 189 if (fname) { 190 switch (flags & O_ACCMODE) { 191 case O_RDONLY: 192 F_SET(t, B_RDONLY); 193 break; 194 case O_RDWR: 195 break; 196 case O_WRONLY: 197 default: 198 goto einval; 199 } 200 201 if ((t->bt_fd = _open(fname, flags, mode)) < 0) 202 goto err; 203 204 } else { 205 if ((flags & O_ACCMODE) != O_RDWR) 206 goto einval; 207 if ((t->bt_fd = tmp()) == -1) 208 goto err; 209 F_SET(t, B_INMEM); 210 } 211 212 if (_fcntl(t->bt_fd, F_SETFD, 1) == -1) 213 goto err; 214 215 if (_fstat(t->bt_fd, &sb)) 216 goto err; 217 if (sb.st_size) { 218 if ((nr = _read(t->bt_fd, &m, sizeof(BTMETA))) < 0) 219 goto err; 220 if (nr != sizeof(BTMETA)) 221 goto eftype; 222 223 /* 224 * Read in the meta-data. This can change the notion of what 225 * the lorder, page size and flags are, and, when the page size 226 * changes, the cachesize value can change too. If the user 227 * specified the wrong byte order for an existing database, we 228 * don't bother to return an error, we just clear the NEEDSWAP 229 * bit. 230 */ 231 if (m.magic == BTREEMAGIC) 232 F_CLR(t, B_NEEDSWAP); 233 else { 234 F_SET(t, B_NEEDSWAP); 235 M_32_SWAP(m.magic); 236 M_32_SWAP(m.version); 237 M_32_SWAP(m.psize); 238 M_32_SWAP(m.free); 239 M_32_SWAP(m.nrecs); 240 M_32_SWAP(m.flags); 241 } 242 if (m.magic != BTREEMAGIC || m.version != BTREEVERSION) 243 goto eftype; 244 if (m.psize < MINPSIZE || m.psize > MAX_PAGE_OFFSET + 1 || 245 m.psize & (sizeof(indx_t) - 1) ) 246 goto eftype; 247 if (m.flags & ~SAVEMETA) 248 goto eftype; 249 b.psize = m.psize; 250 F_SET(t, m.flags); 251 t->bt_free = m.free; 252 t->bt_nrecs = m.nrecs; 253 } else { 254 /* 255 * Set the page size to the best value for I/O to this file. 256 * Don't overflow the page offset type. 257 */ 258 if (b.psize == 0) { 259 b.psize = sb.st_blksize; 260 if (b.psize < MINPSIZE) 261 b.psize = MINPSIZE; 262 if (b.psize > MAX_PAGE_OFFSET + 1) 263 b.psize = MAX_PAGE_OFFSET + 1; 264 } 265 266 /* Set flag if duplicates permitted. */ 267 if (!(b.flags & R_DUP)) 268 F_SET(t, B_NODUPS); 269 270 t->bt_free = P_INVALID; 271 t->bt_nrecs = 0; 272 F_SET(t, B_METADIRTY); 273 } 274 275 t->bt_psize = b.psize; 276 277 /* Set the cache size; must be a multiple of the page size. */ 278 if (b.cachesize && b.cachesize & (b.psize - 1) ) 279 b.cachesize += (~b.cachesize & (b.psize - 1) ) + 1; 280 if (b.cachesize < b.psize * MINCACHE) 281 b.cachesize = b.psize * MINCACHE; 282 283 /* Calculate number of pages to cache. */ 284 ncache = (b.cachesize + t->bt_psize - 1) / t->bt_psize; 285 286 /* 287 * The btree data structure requires that at least two keys can fit on 288 * a page, but other than that there's no fixed requirement. The user 289 * specified a minimum number per page, and we translated that into the 290 * number of bytes a key/data pair can use before being placed on an 291 * overflow page. This calculation includes the page header, the size 292 * of the index referencing the leaf item and the size of the leaf item 293 * structure. Also, don't let the user specify a minkeypage such that 294 * a key/data pair won't fit even if both key and data are on overflow 295 * pages. 296 */ 297 t->bt_ovflsize = (t->bt_psize - BTDATAOFF) / b.minkeypage - 298 (sizeof(indx_t) + NBLEAFDBT(0, 0)); 299 if (t->bt_ovflsize < NBLEAFDBT(NOVFLSIZE, NOVFLSIZE) + sizeof(indx_t)) 300 t->bt_ovflsize = 301 NBLEAFDBT(NOVFLSIZE, NOVFLSIZE) + sizeof(indx_t); 302 303 /* Initialize the buffer pool. */ 304 if ((t->bt_mp = 305 mpool_open(NULL, t->bt_fd, t->bt_psize, ncache)) == NULL) 306 goto err; 307 if (!F_ISSET(t, B_INMEM)) 308 mpool_filter(t->bt_mp, __bt_pgin, __bt_pgout, t); 309 310 /* Create a root page if new tree. */ 311 if (nroot(t) == RET_ERROR) 312 goto err; 313 314 /* Global flags. */ 315 if (dflags & DB_LOCK) 316 F_SET(t, B_DB_LOCK); 317 if (dflags & DB_SHMEM) 318 F_SET(t, B_DB_SHMEM); 319 if (dflags & DB_TXN) 320 F_SET(t, B_DB_TXN); 321 322 return (dbp); 323 324 einval: errno = EINVAL; 325 goto err; 326 327 eftype: errno = EFTYPE; 328 goto err; 329 330 err: if (t) { 331 if (t->bt_dbp) 332 free(t->bt_dbp); 333 if (t->bt_fd != -1) 334 _close(t->bt_fd); 335 free(t); 336 } 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 ((meta = mpool_get(t->bt_mp, 0, 0)) != NULL) { 356 mpool_put(t->bt_mp, meta, 0); 357 return (RET_SUCCESS); 358 } 359 if (errno != EINVAL) /* It's OK to not exist. */ 360 return (RET_ERROR); 361 errno = 0; 362 363 if ((meta = mpool_new(t->bt_mp, &npg)) == NULL) 364 return (RET_ERROR); 365 366 if ((root = mpool_new(t->bt_mp, &npg)) == NULL) 367 return (RET_ERROR); 368 369 if (npg != P_ROOT) 370 return (RET_ERROR); 371 root->pgno = npg; 372 root->prevpg = root->nextpg = P_INVALID; 373 root->lower = BTDATAOFF; 374 root->upper = t->bt_psize; 375 root->flags = P_BLEAF; 376 memset(meta, 0, t->bt_psize); 377 mpool_put(t->bt_mp, meta, MPOOL_DIRTY); 378 mpool_put(t->bt_mp, root, MPOOL_DIRTY); 379 return (RET_SUCCESS); 380 } 381 382 static int 383 tmp(void) 384 { 385 sigset_t set, oset; 386 int fd; 387 char *envtmp = NULL; 388 char path[MAXPATHLEN]; 389 390 if (issetugid() == 0) 391 envtmp = getenv("TMPDIR"); 392 snprintf(path, 393 sizeof(path), "%s/bt.XXXXXXXXXX", envtmp ? envtmp : "/tmp"); 394 395 sigfillset(&set); 396 _sigprocmask(SIG_BLOCK, &set, &oset); 397 if ((fd = mkstemp(path)) != -1) 398 unlink(path); 399 _sigprocmask(SIG_SETMASK, &oset, NULL); 400 return(fd); 401 } 402 403 static int 404 byteorder(void) 405 { 406 u_int32_t x; 407 u_char *p; 408 409 x = 0x01020304; 410 p = (u_char *)&x; 411 switch (*p) { 412 case 1: 413 return (BIG_ENDIAN); 414 case 4: 415 return (LITTLE_ENDIAN); 416 default: 417 return (0); 418 } 419 } 420 421 int 422 __bt_fd(const DB *dbp) 423 { 424 BTREE *t; 425 426 t = dbp->internal; 427 428 /* Toss any page pinned across calls. */ 429 if (t->bt_pinned != NULL) { 430 mpool_put(t->bt_mp, t->bt_pinned, 0); 431 t->bt_pinned = NULL; 432 } 433 434 /* In-memory database can't have a file descriptor. */ 435 if (F_ISSET(t, B_INMEM)) { 436 errno = ENOENT; 437 return (-1); 438 } 439 return (t->bt_fd); 440 } 441