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